MsCl, anhydrous MeCN over molecular sieves, anhydrous pyridine over molecular sieves, anhydrous DMF over molecular sieves, and t-BuOK were purchased from Fluka and used without purification

CHAPTERIV

EXPERIMENTAL SECTION

4.1. General Procedures

All reactions were performed in flame-dried modified Schlenk (Kjeldahl shape) flasks fitted with a glass stopper or rubber septa under a positive pressure of argon.

Air/and moisture-sensitive liquids and solutions were transferred via a syringe. Organic solutions were dried on MgSO4 and concentrated by a rotary evaporator below 40°C at ca. 25 Torr. Flash column chromatography was performed employing 230-400 mesh silica gel. Analytical TLC was performed on Alugram SIL G/UV254 silica gel sheets (Macherey- Nagel) with detection by 0.5% phosphomolybdic acid solution in 95% EtOH.

4.2. Materials

Tri-O-acetyl-D-glucal, MeONa, 1.0 M LHMDS in THF, TBDMS-Cl, 1.0 M TBAF in THF, 1.0 M Bu4NOH in MeOH, were purchased from Aldrich and used without purification. MsCl, anhydrous MeCN over molecular sieves, anhydrous pyridine over molecular sieves, anhydrous DMF over molecular sieves, and t-BuOK were purchased from Fluka and used without purification. Toluene, Et2O and THF were distilled from sodium/benzophenone.

4.3. Instrumentation

Infrared (IR) spectra were obtained using a FTIR spectrophotometer. Data are presented as frequency of absorption (cm^-1). Specific rotations were measured with a digital polarimeter with a 1 dm cell. Proton and carbon-13 nuclear magnetic resonance (¹H NMR and ¹³C NMR) spectra were recorded at 250 and 62.5 MHz, respectively;

chemical shifts are expressed in parts per million ( scale) downfield from tetramethylsilane and refer to residual protium in the NMR solvent (CHCl3:  7.26;

CD3OD:  3.31; C6H6:  7.15). Data are presented as follows: chemical shift, multiplicity (s=singlet, d=doublet, t=triplet, m=multiplet and/or multiple resonances), integration, coupling constant (or W1/2) in Hertz (Hz). Melting points are uncorrected.

4.4. Experimental

Synthesis of trans hydroxy mesylates 2.4b and 2.4a

D-Glucal (3.1). MeONa (0.050 g, 0.92 mmol) was added to a solution of tri-O-acetyl-D-glucal (2.5) (4.0 g, 14.7 mmol) in MeOH (40 mL) and the resulting reaction mixture was stirred at room temperature for 5 h under argon. Evaporation of the organic solvent afforded a product (2.0 g, 93%

yield) consisting of 3.1, practically pure as a syrup: Rf = 0.27 (9:1 CH²Cl2/MeOH); FTIR (neat film) 3398, 2926, 1645, 1413, 1230, 1074, 1015, 824, 735 cm^-1. ¹H NMR (CD3OD)

 6.26 (dd, 1H, J = 6.0, 1.6 Hz), 4.60 (dd, 1H, J = 6.0, 2.2 Hz,), 4.04 (dt, 1H, J = 7.0, 1.9 Hz), 3.85-3.58 (m, 3H), 3.48 (dd, 1H, J = 9.5, 7.0 Hz). ¹³C NMR (CD3OD)  146.5, 106.1, 81.9, 72.5, 72.1, 63.8. Anal.Calcd for C6H10O4: C, 49.31; H, 6.90. Found: C, 49.14; H, 6.78.

6-O-(Benzyl)-D-glucal (3.2b). 1M LHMDS in THF (36.1 mL, 36.1 mmol) was added dropwise at -40°C to a stirred solution of D-glucal (3.1) (4.80 g, 32.9 mmol) in anhydrous DMF (97 mL). BnBr (3.91 mL 32.9 mmol) was added and the reaction mixture was stirred for 6 h allowing the temperature to rise to 0°C. Saturated aqueous NH4Cl (25 mL) and AcOEt (100 mL) were added to the reaction mixture. The organic layer was separated and the aqueous layer extracted with AcOEt (3x25 mL). Combined organic extracts were washed (saturated aqueous NaCl and water) and evaporated to afford a crude product, which was subjected to flash chromatography. Elution with 1:1 hexane/AcOEt afforded the benzyl

O

OH HO

HO

3.1

O

OH BnO

HO

3.2

derivative 3.2 (2.45 g, 32% yield), pure as a solid, mp 38-40°C: Rf = 0.19 (1:1 hexane/AcOEt); FTIR (neat film) 3385, 1647, 1263, 1057 cm^-1. ¹H NMR (CDCl3)  7.24- 7.31 (m, 5H), 6.20 (dd, 1H, J = 6.0, 1.5 Hz), 4.57 (dd, 1H, J = 6.0, 1.8 Hz), 4.52 (d, 1H, J

= 12.0 Hz), 4.46 (d, 1H, J = 12.0 Hz), 4.05-4.17 (m, 1H), 3.57-3.84 (m, 4H). ¹³C NMR (CDCl3)  143.9, 137.4, 128.1, 127.5, 102.5, 77.4, 73.4, 70.0, 69.5, 68.8. Anal.Calcd for C13H16O4: C, 66.09; H, 6.83. Found: C, 66.16; H, 6.91.

3-O-(t-Butyldimethylsilyl)-6-O-(benzyl)-D-glucal-(3.3b).

The treatment of diol 3.2b (2.40 g, 10.2 mmol) in anhydrous DMF (24 mL) with imidazole (1.34 g, 20.4 mmol) and TBDMS-Cl (1.54 g, 10.2 mmol) afforded, after 18 h stirring at room temperature, a crude product (3.47 g) which was subjected to flash chromatography. Elution with 9:1 hexane/AcOEt afforded alcohol 3.3b (3.0 g, 84% yield), pure as a liquid: Rf = 0.33 (9:1 hexane/AcOEt); FTIR (neat film) 3393, 1647, 1447, 1248, 1095 cm^-1. ¹H NMR (CDCl3)  7.24-7.32 (m, 5H), 6.28 (d, 1H, J = 6.0 Hz), 4.58-4.63 (m, 3H), 4.19 (d, 1H, J = 6.0 Hz), 3.92-3.99 (m, 1H), 3.71-3.79 (m, 3H), 0.87 (s, 9H), 0.084 (s, 6H). ¹³C NMR (CDCl3)  143.5, 138.1, 128.6, 127.9, 103.7, 77.1, 73.8, 70.9, 70.0, 69.4, 25.9, 18.2, -4.3. Anal.Calcd for C19H30O4Si: C, 65.10; H, 8.63. Found: C, 64.97; H, 8.51.

3-O-(t-Butyldimethylsilyl)-4-O-mesyl-6-O-(benzyl)-D-glucal (3.4b).

The treatment of alcohol 3.3b (1.20 g, 3.42 mmol) in anhydrous pyridine (15 mL) with MsCl (0.53 mL, 6.84 mmol) afforded, after 18 h stirring at room temperature, a residue which was subjected to flash chromatography. Elution with 9:1 hexane/AcOEt yielded mesylate 3.4b (1.07 g, 72%

yield), pure as a liquid: Rf = 0.11 (9:1 hexane/AcOEt); FTIR (neat film) 1647, 1361, 1253, 1176, 1072 cm^-1. ¹H NMR (CDCl3)  7.24-7.32 (m, 5H), 6.37 (d, 1H, J = 6.4 Hz), 4.71- 4.81 (m, 2H) 4.61 (d, 1H, J=12.3 Hz), 4.52 (d, 1H, J= 12.3 Hz), 4.22-4.42 (m, 2H), 3.81 (dd, 1H, J = 11.0, 7.0 Hz), 3.69 (dd, 1H, J = 11.0, 3.5 Hz), 3.05 (s, 3H), 0.86 (s, 9H), 0.09 (s, 6H). ¹³C NMR (CDCl3)  143.5, 137.7, 128.4, 127.9, 127.7, 101.5, 77.3, 75.5, 73.7, 67.9, 64.7, 38.9, 25.9, 18.0, -4.5. Anal.Calcd for C20H32O6SSi: C, 56.05; H, 7.52. Found:

C, 54.72; H, 7.18.

O

OTBS BnO

HO

3.3

O

OTBS BnO

MsO

3.4

4-O-Mesyl-6-O-(benzyl)-D-glucal (2.4). The treatment of mesylate 3.4b (0.50 g, 1.17 mmol) in anhydrous THF (40 mL) with 1M TBAF in THF (1.17 mL, 1.17 mmol) afforded, after 20 min stirring at 0°C, a residue (0.33 g) which was subjected to flash chromatography. Elution with 1: 1 hexane/AcOEt afforded hydroxy mesylate 2.4 (0.27 g, 74% yield), pure as a solid, mp 39-41°C: Rf = 0.29 (1:1 hexane/AcOEt); FTIR (neat film) 3447, 1649, 1348, 1182 cm^-1. ¹H NMR (CDCl3)  7.28-7.39 (m, 5H), 6.43 (dd, 1H, J = 6.0, 1.5 Hz), 4.78- 4.90 (m, 2H), 4.61 (s, 2H), 4.42-4.51 (m, 1H), 4.11 (dt, 1H, J= 9.3, 3.4 Hz), 3.81-3.85 (m, 2H), 3.14 (s, 3H). ¹³C NMR (CDCl3)  144.4, 137.5, 128.4, 127.9, 127.8, 102.0, 79.1, 75.1, 73.7, 68.1, 67.2, 38.6. Anal.Calcd for C14H18O6S: C, 53.49; H, 5.77. Found: C, 53.17; H, 5.54.

6-O-Benzyl-D-gulal (2.23). A solution of Bu4NBr (0.83 g, 2.56 mmol) in anhydrous THF (10 mL) was treated with Me3SiOK (0.33 g, 2.56 mmol) and the reaction mixture was stirred at room temperature for 10 min.

Filtration through a short (1 cm) Celite column afforded a clear THF solution which was concentrated at reduced pression (rotary evaporator) (final volume about 5 mL) (Solution B, containing Bu4N⁺Me3SiO^-, 4 equiv). A solution of hydroxy mesylate 2.4 (0.20 g, 0.64 mmol) in anhydrous THF (4 mL) was treated with t-BuOK (0.079 g, 0.70 mmol) and the reaction mixture (Solution A) was stirred 15 min at room temperature. Solution B was added dropwise to Solution A and the reaction mixture was stirred 48 h at room temperature. Dilution with Et2O and evaporation of the washed (saturated aqueous NaCl) organic solution afforded a crude liquid product (0.14 g, 93%

yield) consisting of diol 2.23 practically pure (¹H NMR) which was subjected to flash chromatography. Elution with a 3:7 hexane/AcOEt mixture afforded pure diol 2.23 (0.103 g, 68% yield), as a solid, mp 51-53˚C; Rf = 0.26 (3:7 hexane/AcOEt): FTIR:  3435, 1643, 1244, 1093, 1028, 912 cm-1. ¹H NMR (CDCl3) 7.28-7.40 (m, 5H), 6.62 (d, 1H, J

= 5.8 Hz), 4.99 (ddd, 1H, J = 6.8, 5.1, 1.9 Hz), 4.89 (d, 1H, J = 12.0 Hz), 4.67 (d, 1H, J = 12.0 Hz), 3.85-4.00 (m, 5H). ¹³C NMR (CDCl3)  146.8, 128.7, 128.1, 128.0, 100.7, 74.0, 71.9, 71.0, 70.0, 53.4. Anal. Calcd for C13H16O4: C, 66.09; H, 6.83. Found: C, 66.34; H, 7.05.

O

OH BnO

MsO

2.4

O

OH BnO

HO

2.23

3-O-(t-Butyldimethylsilyl)-4-O-mesyl-6-O-benzyl-D-gulal (3.7a).

Following the same procedure used for mesylate 3.4, the treatment of TBS-derivative 3.6a (0.248 g, 0.71 mmol) in anhydrous pyridine (2.2 ml) with MsCl (110 µl, 1.42 mmol) afforded, after 18 h stirring 0°C, mesylate 3.7a (0.249 g, 82% yield), practically pure as a liquid: Rf =0.17 (9:1 hexane/AcOEt); FTIR:  1645, 1472, 1364, 1248, 1178, 1067, 947, 837, 779 cm-1. ¹H NMR (CDCl3) 7.28-7.39 (m, 5H), 6.50 (d, 1H, J = 6.2 Hz), 4.83-4.91 (m, 1H), 4.64- 4.69 (m, 1H), 4.63 (d, 1H, J = 11.8 Hz), 4.56 (d, 1H, J = 11.8 Hz), 4.29 (t, 1H, J = 6.7 Hz), 4.19 (dd, 1H, J = 5.2, 2.7 Hz), 3.76 (dd, 1H, J = 10.0, 6.1 Hz), 3.68 (dd, 1H, J = 10.0, 7.0 Hz), 2.97 (s, 3H), 0.90 (s, 9H), 0.14 (s, 3H), 0.12 (s, 3H). ¹³C NMR (CDCl3)

145.7, 137.7, 128.7, 128.0, 101.0, 75.5, 73.8, 70.1, 68.1, 62.4, 38.3, 26.0, 18.1, -4.2, -4.4. Anal. Calcd for C20H32O6SiS: C, 56.05; H, 7.53. Found: C, 55.78; H, 7.91.

4-O-Mesyl-6-O-benzyl-D-gulal (2.4). The treatment of mesylate 3.7

(0.249 g, 0.58 mmol) in anhydrous THF (20 ml) with 1M TBAF in THF (0.58 ml, 0.58 mmol) yielded, after 20 min stirring at 0°C, a crude product (0.175 g) consisting of hydroxy mesylate 2.4 (¹H NMR) which was subjected to flash chromatography. Elution with a 1:1 hexane/AcOEt afforded hydroxy mesylate 2.4 (0.125 g, 68% yield), pure as a solid, mp 51-53˚C; Rf = 0.28 (1:1 hexane/AcOEt); FTIR 3428, 1645, 1358, 1248, 1178, 1066 cm^-1. ¹H NMR (CDCl3)

7.28-7.39 (m, 5H), 6.58 (d, 1H, J = 6.2 Hz), 4.94-5.03 (m, 1H), 4.76-4.82 (m, 1H), 4.62 (d, 1H, J = 12.0), 4.56 (d, 1H, J = 12.0), 4.18-4.30 (m, 2H), 3.80 (dd, 1H, J = 9.8, 6.3), 3.70 (dd, 1H, J = 9.8, 7.1), 2.99 (s, 3H). ¹³C NMR (CDCl3) 146.7, 137.4, 128.6, 128.1, 99.9, 75.3, 73.7, 70.2, 67.9, 61.6, 38.2. Anal. Calcd for C14H18O6S: C, 53.49; H, 5.77.

Found: C, 53.18; H, 5.43.

BnO O

MsO OH 2.4

O

OTBS BnO

MsO

3.7

Synthesis of trans N-mesyl-O-mesylates 2.32a and 2.32b

Reaction of epoxide 2.1 with TMGA

Typical Procedure. A solution of hydroxy mesylate 2.4 (0.050 g, 0.16 mmol) in MeCN (4 mL) was treated with t-BuOK (0.018 g, 0.16 mmol) and the reaction mixture was stirred 10 min a room temperature. TMGA (0.075 g, 0.48 mmol, 3 equiv) was added and the resulting reaction mixture was stirred 30 min at the same temperature. Dilution with Et2O and evaporation of the washed (saturated aqueous NaCl) organic solution afforded a crude reaction product (0.041 g, 98% yield), essentially consisting of trans azido alcohol 3.5

(¹H NMR), which was subjected to flash chromatography. Elution with a 7:3 hexane/AcOEt mixture afforded 6-O-(benzyl)-3-deoxy-3-azido-D-gulal (3.5) (0.026 g, 63% yield), pure as a liquid: Rf = 0.29 (7:3 hexane/AcOEt); FTIR  3391, 2102, 1643, 1093 cm-1. ¹H NMR (CDCl3) 7.25-7.41 (m, 5H), 6.70 (d, 1H, J = 6.1 Hz) 4.88 (td, 1H, J = 6.1, 1.5 Hz), 4.62 (d, 1H, J = 11.9), 4.56 (d, 1H, J = 11.9 Hz), 3.82-3.91 (m, 4H), 3.70-3.77 (m, 1H). ¹³C NMR (CDCl3)  148.2, 137.2, 128.7, 128.2, 127.9, 95.2, 74.0, 72.0, 70.7, 68.5, 55.6. Anal.Calcd for C13H15N3O3: C 59.76; H, 5.79; N, 16.08. Found: C, 59.67; H, 5.51; N, 15.89.

Reaction of epoxide 2.1 with TMGA

Following the above described typical procedure, the treatment of a solution of hydroxy mesylate 2.4 (0.062 g, 0.197 mmol) in anhydrous MeCN (4 mL) with t-BuOK (0.022 g, 0.197 mmol) and TMGA (0.093 g, 0.59 mmol, 4 equiv) afforded, after 30 min stirring at room temperature, a crude reaction product consisting of an 85:15 mixture of trans azido alcohol 3.8 and cis azido alcohol (¹H NMR), which was subjected to flash chromatography. Elution with an 8:2 hexane/AcOEt mixture afforded 6-O-(benzyl)-3-deoxy-3-azido-D-glucal (3.8) (0.015 g, 31% yield), pure as a liquid: Rf = 0.58 (8:2 hexane/AcOEt). ¹H NMR (CDCl3)

7.21-7.46 (m, 5H), 6.44 (d, 1H, J = 6.0, 1.5 Hz) 4.69 (d, 1H, J = 6.0, 1.9 Hz), 4.66 (d, 1H, J = 12.0), 4.56 (d, 1H, J = 12.0 Hz), 3.68-4.08 (m, 5H), 2.82 (bs, 1H). Anal.Calcd for C13H15N3O3: C 59.76; H, 5.79; N, 16.08. Found: C, 59.83; H, 5.65; N, 16.19.

BnO O

HO N₃ 3.5

BnO O

HO N₃ 3.8

6-O-Benzyl-3-deoxy-3-amino-D-gulal (2.45). Resin supported PPh3

(3 mmol/1g) (1.2g, 3.61 mmol) was first washed with CH2Cl2, acetone and methanol, dried at 60°C three hours and then allowed to swell in THF/H2O 20:1 (20 mL) for 30 min without stirring, before the start of the reaction. A solution of trans azido alcohol 3.8 (0.55g, 2.12 mmol) in THF (4mL) was added dropwise and the reaction mixture was stirred 48 h at room temperature.

Dilution with Et2O and evaporation of the filtered organic solution afforded a crude reaction product (0.40 g, 80% yield) consisting of trans amino alcohol 2.45a (¹H NMR), practically pure as a liquid, which was directly used in the next step without any further purification: Rf = 0.19 (93:7 CH2Cl2/MeOH); FTIR (neat film)  3425, 3364, 1647, 1591, 1240, 1091 cm-1. ¹H NMR (CDCl3)  7.28-7.40 (m, 5H), 6.51 (d, 1H, J = 6.1 Hz), 4.86 (td, 1H, J = 6.1, 1.4 Hz), 4.65 (d, 1H, J =12.0 Hz), 4.57 (d, 1H, J =12.0 Hz), 3.95-4.03 (m, 1H), 3.73-3.93 (m, 3H), 3.20-3.27 (m, 1H). ¹³C NMR (CDCl3)  145.08, 134.17, 128.75, 128.20, 128.06, 99.26, 74.21. 72.73, 71.23, 69.67, 36.95. Anal.Calcd for C13H17NO3: C, 66.36; H, 7.28; N, 5.95. Found: C, 66.28; H, 7.01; N, 5.64.

6-O-Benzyl-3-deoxy-3-N-(mesylamino)-4-O-mesyl-D-gulal (2.32).

A solution of amino alcohol 2.45 (0.436 g, 1.85 mmol) in anhydrous pyridine (4 mL) was treated at 0°C with MsCl (0.43 ml, 5.55 mmol) and the reaction mixture was stirred 7 h at room temperature. Dilution with CH2Cl2 (60 mL) and evaporation of the washed (water) organic solution afforded a crude residue (0.71 g) consisting of trans N,O-dimesylate 4.2 which was subjected to flash chromatography. Elution with a 3:4:3 hexane/CH2Cl2/AcOEt mixture yielded trans N,O-dimesylate 4.2 (0.528 g. 73% yield), pure as a solid, mp 158-161°C: Rf = 0.22 (4:6 hexane/AcOEt); ^[α] 20

D +96.3 (c 0.20, CHCl3). FTIR (nujol)  3369, 1649, 1421, 1364, 1335, 1265, 1179, 950, 896., 1750, 1732, 1454, 1437, 1325, 1151, 1109, 976 cm^-1. 1H NMR (C6D6)  7.04-7.27 (m, 5H), 6.12 (d, 1H, J = 6.2 Hz), 5.00 (d, 1H, J = 2.7 Hz), 4.27 (d, 1H, J = 11.5 Hz), 4.18 (d, 1H, J = 11.5 Hz), 4.18-4.26 (m, 1H), 3.88-3.99 (m, 1H), 3.73-3.87 (m, 2H), 3.57-3.65 (m, 2H), 2.33 (s, 3H), 2.27 (s, 3H). 1H NMR (CDCl3)

7.28-7.39 (m, 5H), 6.60 (d, 1H, J = 6.2 Hz), 4.93-4.98 (m, 1H), 4.84 (ddd, 1H, J = 6.2,

O

NH₂ BnO

HO

2.45

BnO O

MsO

NHMs 2.32

5.3, 1.7 Hz), 4.59 (s, 2H), 4.52 (d, 1H, J = 6.4 Hz), 4.01-4.17 (m, 2H), 3.78 (dd, 1H, J = 9.8, 6.0 Hz), 3.70 (dd, 1H, J = 9.8, 6.8 Hz), 3.06 (s, 3H), 3.05 (s, 3H). ¹³C NMR (CDCl3)

 147.43, 137.38, 128.66, 128.17, 96.64, 75.16, 73.83, 70.45, 67.94, 47.47, 41.32, 38.17.

Anal.Calcd for C15H21NO7S2: C, 46.02; H, 5.41; N, 3.58. Found: C, 46.37; H, 5.18; N, 3.29.

6-O-Benzyl-3-deoxy-3-amino-D-glucal (2.45). Following the same procedure used for trans amino alcohol 2.45a, resin supported PPh3 (3 mmol/1g) (1.3g, 3.91 mmol) was first washed with CH2Cl2, acetone and methanol, dried at 60°C three hours and then allowed to swell in THF/H2O 20:1 (20 mL) for 30 min without stirring, before the start of the reaction. A solution of trans azido alcohol 3.8b (0.601 g, 2.30 mmol) in THF (4mL) was added dropwise and the reaction mixture was stirred 48 h at room temperature. Dilution with Et2O and evaporation of the filtered organic solution afforded a crude reaction product (0.38 g, 70% yield) consisting of trans amino alcohol 2.45b (¹H NMR), practically pure as a liquid, which was directly used in the next step without any further purification:

[α] 20

D -11.6 (c 0.56, CHCl3); Rf = 0.18 (9:1 CH2Cl2/MeOH); FTIR (neat film)  3331, 1651, 1494, 1454, 1323, 1234, 1074 cm-1. ¹H NMR (CDCl3)  7.27-7.37 (m, 5H), 6.34 (d, 1H, J = 5.8 Hz), 5.90 (bs, 3H), 4.74 (d, 1H, J = 5.8 Hz), 4.56 (s, 2H), 3.64-3.97 (m, 5H). ¹³C NMR (CDCl3)  146.2, 137.9, 128.7, 128.0, 98.6, 73.9, 69.0, 67.7, 52.4, 36.8.

Anal.Calcd for C13H17NO3: C, 66.35; H, 7.29; N, 5.96. Found: C, 66.42; H, 7.02; N, 5.79.

6-O-Benzyl-3-deoxy-3-N-(mesylamino)-4-O-mesyl-D-glucal (2.32).

Following the same procedure used for trans N,O-dimesylate 2.32, the treatment of amino alcohol 2.45 (0.577 g, 2.46 mmol) in anhydrous pyridine (5.5 mL) with MsCl (0.57 ml, 7.38 mmol) afforded, after 7 h stirring at 0°C, a crude residue (0.94 g, 98% yield) consisting of trans N,O-dimesylate 2.32, which was subjected to flash chromatography. Elution with a 2:5:3 hexane/CH2Cl2/AcOEt mixture yielded trans N,O-dimesylate 2.32 (0.72 g, 75% yield), pure as a solid, mp 95-98°C: ^[α] 20

D +38.4 (c 0.97, CHCl3); Rf = 0.24 (1:1

O

NH₂ BnO

HO

2.45

O

NHMs BnO

MsO

2.32

hexane/AcOEt); FTIR (nujol)  3252, 1456, 1375, 1338, 1317, 1251, 1172 cm-1. ¹H NMR (CDCl3)  7.27-7.40 (m, 5H), 6.42 (dd, 1H, J = 6.0, 1.9 Hz), 5.20 (d, 1H, J = 9.2 Hz, NH), 4.89 (dd, 1H, J = 8.4, 7.6), 4.72 (dd, 1H, J = 6.1, 2.6 Hz), 4.62 (d, 1H, J = 11.6 Hz), 4.55 (d, 1H, J = 11.6 Hz), 4.10-4.32 (m, 2H), 3.81 (d, 2H, J = 3.1 Hz), 3.14 (s, 3H), 2.98 (s, 3H). ¹³C NMR (CDCl3)  145.4, 137.3, 128.6, 128.1, 128.0, 100.2, 76.1, 75.7, 74.0. 68.1, 51.8, 42.0, 39.2. Anal.Calcd for C15H21NO7S2: C, 46.03; H, 5.41; N, 3.58. Found: C, 45.93; H, 5.17; N, 3.21.

Synthesis of trans N-nosyl-O-mesylate 2.47a

6-O-Benzyl-3-deoxy-3-N-(nosylamino)-D-gulal (2.46a). A solution of amino alcohol 2.45a (0.117 g, 0.50 mmol) in anhydrous CH2Cl2 (1.7 mL) was treated at room temperature with Et3N (0.076 mL, 0.55 mmol) and NsCl (0.121 g, 0.55 mmol) and the reaction mixture was stirred 2 h at the same temperature. Dilution with CH2Cl2 (30 mL) and evaporation of the washed (saturated aqueous NaHCO3, 1x5 mL, and saturated aqueous NaCl, 1x5 mL) organic solution afforded a crude residue (0.214 g) consisting of the N-nosyl derivative 2.46a, which was subjected to flash chromatography. Elution with an 1:1 hexane/AcOEt mixture yielded the N-nosylate 2.46a (0.108 g, 53% yield), pure as a yellow liquid: ^[α] 20

D +25.2 (c 1.04, CHCl3); Rf = 0.19 (1:1 hexane/AcOEt); FTIR (neat film)  3479, 3350, 1650, 1540, 1450, 1360, 1240, 1150, 1020 cm^-1. ¹H NMR (CDCl3)  8.10-8.18 (m, 1H), 7.82- 7.90 (m, 1H), 7.65-7.80 (m, 2H), 7.24-7.43 (m, 5H), 7.00 (d, 1H, J = 7.5 Hz), 5.35-5.42 (m, 1H, NH), 4.62 (d, 1H, J = 12.0 Hz), 4.52 (d, 1H, J = 12.0 Hz), 4.36 (t, 1H, J = 3.7 Hz), 3.84-3.92 (m, 1H), 3.74 (unresolved d, 2H, J = 3.7 Hz), 3.56-3.81 (m, 2H), 3.18 (bs, 1H, OH). ¹³C NMR (CDCl3)  150.0, 133.6, 133.0, 131.0, 128.7, 128.3, 128.0, 125.6, 92.5, 77.4, 74.2, 69.8, 64.4, 51.2. Anal.Calcd for C19H20N2O7S: C, 54.28; H, 4.79; N, 6.66.

Found: C, 54.03; H, 4.65; N, 6.56.

BnO O

HO

NHNs 2.46

6-O-Benzyl-3-deoxy-3-N-(nosylamino)-4-O-mesyl-D-gulal (2.47).

A solution of the N-nosyl derivative 2.46a (2.13 g, 5.07 mmol) in anhydrous CH2Cl2 (27 mL) was treated at 0°C with anhydrous pyridine (1.22 mL, 15.21 mmol) and MsCl (0.78 mL, 10.14 mmol) and the reaction mixture was stirred 18 h at 0°C. Dilution with CH2Cl2 (200 mL) and evaporation of the washed (water, 2x15 mL) organic solution afforded a crude residue (2.9 g) consisting of trans N-nosyl-O-mesyl derivative 2.47 which was subjected to flash chromatography. Elution with a 4:3:3 hexane/ CH2Cl2/AcOEt mixture yielded the trans N- nosyl-O-mesylate 2.47 (1.26 g, 50% yield), pure as a pale yellow solid, mp 102-105°C:

[α] 20

D +89.3 (c 0.61, CHCl3); Rf = 0.33 (1:1 hexane/AcOEt); FTIR (nujol)  3319, 1647, 1543, 1371, 1251, 1178 cm^-1. ¹H NMR (CDCl3)  8.22-8.31 (m, 1H), 7.61-7.92 (m, 3H), 7.23-7.43 (m, 5H), 6.57 (d, 1H, J = 5.9 Hz), 5.39 (d, 1H, J = 4.9 Hz, NH), 4.96-5.03 (m, 1H), 4.63 (td, 1H, J = 5.9, 1.7 Hz), 4.52 (s, 2H), 4.22 (t, 1H, J = 6.8 Hz), 3.96-4.05 (m, 1H), 3.74 (dd, 1H, J = 9.8, 6.0 Hz), 3.64 (dd, 1H, J = 9.8, 7.5 Hz), 3.03 (s, 3H). ¹³C NMR (CDCl3)  148.2, 137.4, 134.3, 133.4, 132.2, 128.7, 128.3, 125.7, 95.5, 73.9, 73.8, 70.0, 67.4, 47.7, 37.9. Anal.Calcd for C20H22N2O9S2: C, 48.19; H, 4.45; N, 5.62. Found: C, 48.31; H, 4.49; N, 5.70.

Formation in situ of N-mesyl aziridines 2.2 and 2.2 and N-nosyl aziridine 2.3

Aziridines 2.2, 2.2 and 2.3 were prepared in situ by cyclization, at room temperature, of the corresponding stable precursor, the trans N,O-dimesylates 2.32, 2.32, and N-nosyl-O-mesylate 2.47 respectively, by means of the same base (t-BuOK, t-BuOLi or LiH) used for the generation of the corresponding metal enolate. Only in two cases corresponding to the reaction with Li-enolate of dibenzoylmethane, t-BuOK (1.3 equiv) was exclusively used for the formation in situ of the aziridine (2.2 and 2.2) from the corresponding stable precursor, whereas t-BuOLi (3 equiv) was exclusively used for the generation of Li-enolate.

O

NHNs BnO

MsO

2.47

Reaction of N-mesyl aziridine 2.2 with K-enolate of dimethylmalonate in dry toluene by t-BuOK, as the only base

A solution of trans N,O-dimesylate (+)-2.32 (0.069 g, 0.176 mmol) in dry toluene (2.0 mL) was treated at room temperature with t-BuOK (0.050 g, 0.44 mmol, 2.5 equiv) in the presence of dimethylmalonate (0.058 g, 0.44 mmol, 2.5 equiv). After 3 h stirring at the same temperature, the reaction mixture was partitioned between Et2O (20 mL) and brine (5 mL), and the aqueous layer was further extracted with Et2O (2 x 5 mL).

Evaporation of the combined organic extracts afforded a crude reaction product consisting of the excess of dimethyl malonate and a 68:32 mixture of 3-(dimethoxycarbonylmethyl)-

D-glucal derivative (–)-3.10 (anti-1,2-addition product) and 2,5-dihydropyrrole derivative

(+)-3.9 (rearranged product) (¹H NMR) which was subjected to flash chromatography.

Elution with a 4:6 hexane/AcOEt mixture afforded pure 3-(dimethoxycarbonylmethyl)-D- glucal derivative (–)-6 (0.036 g, 48% yield) and 2,5-dihydropyrrole derivative (+)-5 (0.016 g, 21% yield

6-O-Benzyl-3,4-dideoxy-4-(N-mesylamino)-3-(dimethoxy- carbonylmethyl)-D-glucal [(–)-3.10], an oil, Rf = 0.45 (3:7 hexane/AcOEt); ^[α] 20

D –6.4 (c 0.26, CHCl3). FTIR (neat)  3299, 1750, 1732, 1454, 1437, 1325, 1151, 1109, 976 cm^-1; ¹H NMR (CDCl3)  7.25-7.38 (m, 5H), 6.40 (dd, 1H, J = 6.2, 2.2 Hz), 4.75 (d, 1H, J = 9.1 Hz), 4.68 (dd, 1H, J = 6.2, 2.8 Hz), 4.62 (d, 1H, J = 11.8 Hz), 4.54 (d, 1H, J = 11.8 Hz), 3.87-4.13 (m, 2H), 3.84 (d, 1H, J = 5.8 Hz), 3.78 (dd, 2H, J = 4.6, 2.0 Hz), 3.73 (s, 3H), 3.70 (s, 3H), 3.05 (s, 3H), 2.88-3.00 (m, 1H). ¹³C NMR (CDCl3) 169.1, 167.9, 144.4, 137.6, 128.7, 128.0, 99.5, 77.6, 73.9, 68.9, 53.0, 52.8, 52.2, 51.1, 42.1, 39.1. Anal. Calcd for C19H25NO8S: C, 53.39; H, 5.89; N, 3.28. Found: C, 53.57; H, 5.55; N, 3.01.

(+)-3.9 N Ms

CHCO₂Me BnO

OH

5S 2R 6S

BnO O

MsHN

CH(CO₂Me)₂ 4S

3S

(-)-3.10

BnO O

MsHN

CH(CO₂Me)₂ 4S

3S

(-)-3.10

(2R,5S,6S)-5-[2-(benzyloxy)-1-hydroxy-ethyl]-2- (dimethoxycarbonylmethyl)-1-mesyl-2,5-dihydro-1H- pyrrole [(+)-3.9], an oil, Rf = 0.37 (3:7 hexane/AcOEt);

[α] 20

D +5.4 (c 0.30, CHCl3). FTIR (neat)  3412, 1752, 1735, 1437, 1421, 1342, 1265, 1165, 1100, 1026, 896 cm^-1; ¹H NMR (CDCl3)  7.28-7.38 (m, 5H), 6.03 (dt, 1H, J = 6.3, 1.9 Hz), 5.91 (dt, 1H, J = 6.3, 1.8 Hz), 4.93 (dq, 1H, J = 7.0, 1.8 Hz), 4.56 (d, 1H, J = 11.9 Hz), 4.53 (d, 1H, J = 11.9 Hz), 4.48-4.52 (m, 1H), 4.02- 4.10 (m, 1H), 3.91 (d, 1H, J = 7.0 Hz), 3.77 (s, 3H), 3.73 (s, 3H), 3.62 (dd, 1H, J = 8.8, 5.5 Hz), 3.55 (dd, 1H, J = 8.8, 4.5 Hz), 3.01-3.08 (m, 1H), 2.79 (s, 3H). ¹³C NMR (CDCl3)  168.1, 137.8, 129.7, 128.6, 128.1, 128.0, 73.7, 71.5, 70.9, 66.3, 57.2, 53.2, 52.8, 34.2, 29.9. Anal. Calcd for C19H25NO8S: C, 53.39; H, 5.89; N, 3.28. Found: C, 53.21; H, 5.64; N, 3.12.

Reaction of N-mesyl aziridine 2.2 with Li-enolate of dimethylmalonate in dry toluene by LiH, as the only base

A solution of trans N,O-dimesylate (+)-2.32 (0.035 g, 0.0895 mmol) in dry toluene (1.0 mL) was treated at room temperature with LiH (0.003 g, 0.358 mmol, 4 equiv) in the presence of dimethylmalonate (0.035 g, 0.268 mmol, 3 equiv). After 3 h stirring at the same temperature, the reaction mixture was partitioned between Et2O (20 mL) and brine (5 mL), and the aqueous layer was further extracted with Et2O (2 x 5 mL).

Evaporation of the combined organic extracts afforded a crude product consisting of the excess of dimethyl malonate and a 26:74 mixture of 3-(dimethoxycarbonylmethyl)-D- glucal derivative (–)-3.10 and 2,5-dihydropyrrole derivative (+)-3.9 (¹H NMR).

Reaction of N-mesyl aziridine 2.2 with Li-enolate of dimethylmalonate in dry toluene by t-BuOLi, as the only base

(+)-3.9 N Ms

CHCO₂Me BnO

OH

5S 2R 6S

(+)-3.15 N Ms

CH(CO₂Me)₂ BnO

OH

5R 2S 6S

BnO O

(+)-3.16 MsHN

CH(CO₂Me)₂

A solution of N,O-dimesylate (+)-2.32 (0.035 g, 0.0895 mmol) in dry toluene (1.0 mL) was treated at room temperature with t-BuOLi (0.022 g, 0.268 mmol, 3.0 equiv) in the presence of dimethylmalonate (0.035 g, 0.268 mmol, 3.0 equiv). After 3 h stirring at the same temperature, the reaction mixture was partitioned between Et2O (20 mL) and brine (5 mL), and the aqueous layer was further extracted with Et2O (2 x 5 mL).

Evaporation of the combined organic extracts afforded a crude product consisting of the excess of dimethyl malonate and a 59:41 mixture of 3-(dimethoxycarbonylmethyl)-D- gulal derivative (+)-3.16 (anti-1,2-addition product) and 2,5-dihydropyrrole derivative (+)- 3.15 (¹H NMR) which was subjected to flash chromatography. Elution with an 1:1 CH2Cl2/i-Pr2O mixture afforded pure 3-(dimethoxycarbonylmethyl)-D-gulal derivative (+)- 3.16 (0.014 g, 36% yield) and 2,5-dihydropyrrole derivative (+)-3.15 (0.010 g, 26%

yield

6-O-Benzyl-3,4-dideoxy-4-(N-mesylamino)-(dimethoxy- -carbonyl methyl)-D-gulal [(+)-3.16]: an oil, Rf = 0.39 [1:1 CH2Cl2/(i-Pr)2O]; ^[α] 20

D +75.7 (c 0.94, CHCl3). FTIR (neat)  3294, 1750, 1735, 1436, 1329, 1266, 1156, 1043, 979 cm^-1; ¹H NMR (CDCl3)  7.25-7.40 (m, 5H), 6.50 (dd, 1H, J = 6.2, 1.2 Hz), 4.75 (d, 1H, J = 9.9 Hz, NH), 4.65 (ddd, 1H, J = 6.2, 4.7, 1.7 Hz), 4.57 (s, 2H), 3.88-3.99 (m, 1H), 3.76 (s, 3H), 3.75 (s, 3H), 3.68-3.79 (m, 3H), 3.29 (d, 1H, J = 10.7 Hz), 3.13 (s, 3H), 2.82-2.95 (m, 1H). ¹³C NMR (CDCl3)  168.1, 167.6, 146.1, 137.8, 128.6, 128.2, 128.0, 98.2, 73.9, 72.4, 69.5, 56.7, 53.2, 53.0, 49.6, 42.0, 38.0. Anal. Calcd for C19H25NO8S: C, 53.39; H, 5.89; N, 3.28. Found: C, 53.07; H, 5.56; N, 2.95.

(2S,5R,6S)-5-[2-(benzyloxy)-1-hydroxy-ethyl]-2- (dimethoxycarbonylmethyl)-1-mesyl-2,5-dihydro-1H- pyrrole [(+)-3.15]: an oil, Rf = 0.31 [1:1 CH2Cl2/(i- Pr)2O]; ^[α^{] 20}_D +27.4 (c 0.13, CHCl3). FTIR (neat)  3401, 1749, 1736, 1422, 1265, 1161, 1071, 896 cm^-1; ¹H NMR (CDCl3)  7.27-7.41 (m, 5H), 6.05 (dt, 1H, J = 6.2, 1.9 Hz), 5.82 (dt, 1H, J = 6.2, 1.8 Hz), 5.02 (dq, 1H, J = 7.5, 1.8 Hz), 4.64 (d, 1H, J = 11.7 Hz), 4.52 (d, 1H, J = 11.7

BnO O

(+)-3.16 MsHN

CH(CO₂Me)₂

(+)-3.15 N Ms

CH(CO₂Me)₂ BnO

OH

5R 2S 6S

Hz), 4.46-4.64 (m, 1H), 3.91 (d, 1H, J = 7.5 Hz), 3.76 (s, 3H), 3.72 (s, 3H), 3.52-3.77 (m, 3H), 3.21-3.30 (m, 1H), 2.83 (s, 3H). ¹³C NMR (CDCl3)  167.7, 167.6, 138.1, 129.5, 128.9, 128.7, 128.2, 128.0, 73.8, 73.2, 71.5, 70.6, 67.1, 57.4, 53.2, 52.7, 34.8. Anal. Calcd for C19H25NO8S: C, 53.39; H, 5.89; N, 3.28. Found: C, 53.44; H, 5.59; N, 3.08.

Reaction of N-mesyl aziridine 2.2 with Li-enolate of dimethylmalonate in dry toluene by LiH, as the only base

A solution of N,O-dimesylate (+)-2.32(0.035 g, 0.0895 mmol) in dry toluene (1.0 mL) was treated at room temperature with LiH (0.003 g, 0.358 mmol, 4.0 equiv) in the presence of dimethylmalonate (0.035 g, 0.268 mmol, 3.0 equiv). After 3 h stirring at the same temperature, the reaction mixture was partitioned between Et2O (20 mL) and brine (5 mL), and the aqueous layer was further extracted with Et2O (2 x 5 mL).

Evaporation of the combined organic extracts afforded a crude product consisting of the excess of dimethyl malonate and an 85:15 mixture of (+)-3.16 and (+)-3.15 (¹H NMR).

Reaction of N-mesyl aziridine 2.2 with K-enolate of dimethylmalonate in dry toluene by t-BuOK, as the only base

A solution of N,O-dimesylate (+)-2.32(0.035 g, 0.0895 mmol) in dry toluene (1.0 mL) was treated at room temperature with t-BuOK (0.025 g, 0.223 mmol, 2.5 equiv) in the presence of dimethylmalonate (0.029 g, 0.223 mmol, 2.5 equiv). After 3 h stirring at the same temperature, the reaction mixture was partitioned between Et2O (20 mL) and brine (5 mL), and the aqueous layer was further extracted with Et2O (2 x 5 mL).

Evaporation of the combined organic extracts afforded a crude product consisting of the excess of dimethyl malonate and a 93:7 mixture of (+)-3.16 and (+)-3.15 (¹H NMR).

Reaction of N-mesyl aziridine 2.2 with K-enolate of dibenzoylmethane in dry toluene by t-BuOK, as the only base

N Ms

CH(COPh)₂ BnO

OH

(+)-3.21

BnO O

MsHN

CH(COPh)₂ (-)-3.22

BnO O

3.23

CH(COPh)₂

MsHN

A solution of trans N,O-dimesylate (+)-2.32 (0.069 g, 0.176 mmol) in dry toluene (2.0 mL) was treated at room temperature with t-BuOK (0.049 g, 0.44 mmol, 2.5 equiv) in the presence of dibenzoylmethane (0.099 g, 0.44 mmol, 2.5 equiv). After 3 h stirring at the same temperature, the reaction mixture was partitioned between Et2O (20 mL) and brine (5 mL), and the aqueous layer was further extracted with Et2O (2 x 5 mL).

Evaporation of the combined organic extracts afforded a crude product consisting of the excess of dibenzoylmethane and a 42:42:16 mixture of 3-(dibenzoylmethyl)-D-glucal derivative (–)-3.22 (anti-1,2-addition product), 2,5-dihydropyrrole derivative (+)-3.21 and

-C-glycoside 3.23 (anti-1,4-addition product) (¹H NMR), which was subjected to preparative TLC using a 4:3:3 hexane/CH2Cl2/(i-Pr)2O mixture, as the eluant (6 runs).

Without considering the decidedly fastest moving band containing the excess of dibenzoylmethane, extraction of the remaining three most intense bands (the faster moving band contained (+)-3.21 and the slower moving band contained 3.23afforded pure 3-(dibenzoylmethyl)-D-glucal derivative (–)-3.22 (0.028 g, 30% yield), 2,5- dihydropyrrole derivative (+)-3.21 (0.022 g, 24% yield and  -C-glycoside 3.23 (0.008 g, 9% yield

6-O-Benzyl-3,4-dideoxy-4-(N-mesylamino)-3-(dibenzoyl- methyl)-D-glucal [(–)-3.22]: an oil, Rf = 0.30 [3:4:3 hexane/CH2Cl2/(i-Pr)2O]; ^[α] 20

D –37.4 (c 0.85, CHCl3).

FTIR (neat)  3436, 1685, 1666, 1449, 1384, 1265, 1151, 1072, 899 cm^-1; ¹H NMR (CDCl3)  7.86-7.96 (m, 4H), 7.18-7.62 (m, 11H), 6.34 (dd, 1H, J = 6.3, 2.3 Hz), 5.90 (d, 1H, J = 6.9 Hz), 4.87 (d, 1H, J = 8.7 Hz), 4.48-4.65 (m, 1H), 4.55 (s, 2H), 3.94-4.19 (m, 2H), 3.86 (dd, 1H, J = 11.1 Hz, 4.3 Hz), 3.78 (dd, 1H, J = 11.1, 5.0 Hz), 3.30-3.44 (m, 1H), 3.06 (s, 3H). ¹³C NMR (CDCl3)  195.8, 195.4, 143.7, 137.4, 133.8, 133.6, 129.0, 128.8, 128.6, 128.1, 128.0, 100.1, 77.3, 74.0, 68.7, 57.0, 51.7, 41.4, 39.1. Anal. Calcd for C29H29NO6S: C, 67.03; H, 5.63; N, 2.70. Found: C, 66.81; H, 5.34;

N, 2.35.

BnO O

MsHN

CH(COPh)₂ (-)-3.22

(2R,5S,6S)-5-[2-(benzyloxy)-1-hydroxy-ethyl]-2- (dibenzoylmethyl)-1-mesyl-2,5-dihydro-1H-pyrrole [(+)-3.21]: an oil, Rf = 0.37 [3:4:3 hexane/CH2Cl2/(i- Pr)2O]; ^[α] 20

D +79.2 (c 1.37, CHCl3). FTIR (neat)  3435, 1694, 1670, 1449, 1343, 1265, 1164, 895 cm^-1; ¹H NMR (CDCl3)  8.08-8.18 (m, 2H) 7.88-7.98 (m, 2H), 7.21-7.66 (m, 11H), 6.32 (dt, 1H, J = 6.3, 1.8 Hz), 6.15 (d, 1H, J

= 5.1 Hz), 5.90 (dt, 1H, J = 6.3, 2.1 Hz), 5.18-5.23 (m, 1H), 4.40 (d, 1H, J = 11.5 Hz), 4.34 (d, 1H, J = 11.5 Hz), 4.28-4.33 (m, 1H), 3.45-3.59 (m, 1H), 3.40 (dd, 1H, J = 9.7, 5.6 Hz), 3.30 (dd, 1H, J = 9.7, 4.6 Hz), 2.79 (s, 3H), 2.16 (d, 1H, J = 5.4 Hz). ¹³C NMR (CDCl3)  194.6, 137.9, 136.9, 136.3, 134.2, 133.8, 130.7, 129.6, 129.3, 128.9, 128.6, 127.9, 127.2, 73.6, 73.0, 71.5, 70.6, 69.2, 61.0, 32.5. Anal. Calcd for C29H29NO6S: C, 67.03; H, 5.63; N, 2.70. Found: C, 66.74; H, 5.29; N, 2.44.

(2R,5S,6S)-6-(Benzyloxymethyl)-5-(N-mesylamino)-2- (dibenzoylmethyl)-2H-5,6-dihydropyran (3.23): an oil, Rf = 0.21 [3:4:3 hexane/CH2Cl2/(i-Pr)2O]. FTIR (neat)  3430, 1653, 1675, 1421, 1265, 1071, 896 cm^-1; ¹H NMR (CDCl3)  7.87-8.03 (m, 4H), 7.12-7.61 (m, 11H), 6.05 (dt, 1H, J = 10.4, 1.7 Hz), 5.85 (dt, 1H, J = 10.4, 1.9 Hz), 5.56 (d, 1H, J = 8.2 Hz), 5.15-5.26 (m, 1H), 4.37 (d, 1H, J = 12.0 Hz), 4.30 (d, 1H, J = 12.0 Hz), 4.25-4.42 (m, 1H), 4.02-4.20 (m, 1H), 3.61 (d, 2H, J

= 4.0 Hz), 3.41-3.52 (m, 1H), 2.93 (s, 3H). ¹³C NMR (CDCl3)  193.1, 137.0, 133.7, 133.3, 130.5, 129.1, 128.9, 128.5, 127.8, 75.6, 73.4, 69.4, 60.6, 48.0, 41.5, 33.8. Anal.

Calcd for C29H29NO6S: C, 67.03; H, 5.63; N, 2.70. Found: C, 66.95; H, 5.49; N, 2.38.

Treatment of -C-glycoside 3.23 with t-BuOK in dry toluene

A solution of -C-glycoside 3.23 (0.020 g, 0.385 mmol) in dry toluene (0.2 ml)

N Ms

CH(COPh)₂ BnO

OH

(+)-3.21

BnO O

3.23

CH(COPh)₂

MsHN

N Ms

CH(COPh)₂

(+)-3.21 BnO O

MsHN

CH(COPh)₂

3.23

toluene

t-BuOK BnO OH

was treated at room temperature with t-BuOK (0.0065 g, 0.058 mmol, 1.5 equiv) and the reaction mixture was stirred at the same temperature for 24 h. Evaporation of the filtered organic solution afforded 2,5-dihydropyrrole derivative (+)-3.21 (0.012 g, 75% yield . In some cases, 2,5-dihydropyrrole derivative (+)-3.23 was found contaminated by some amount of the corresponding 2-(benzoylmethyl) derivative (+)-3.24 (vide infra).

Reaction of N-mesyl aziridine 2.2 with K-enolate of dibenzoylmethane in dry THF by t-BuOK, as the only base

A solution of trans N,O-dimesylate (+)-2.32 (0.035 g, 0.0895 mmol) in dry THF (1.0 mL) was treated at room temperature with t-BuOK (0.025 g, 0.223 mmol, 2.5 equiv) in the presence of dibenzoylmethane (0.050 g, 0.223 mmol, 2.5 equiv). After 3 h stirring at the same temperature, the reaction mixture was partitioned between Et2O (20 mL) and brine (5 mL), and the aqueous layer was further extracted with Et2O (2 x 5 mL).

Evaporation of the combined organic extracts afforded a crude product consisting of the excess of dibenzoylmethane and a 40:60 mixture of 3-(dibenzoylmethyl)-D-glucal derivative (–)-3.22 (anti-1,2-addition product) and 2,5-dihydropyrrole derivative (+)-3.21 (¹H NMR) which was subjected to preparative TLC using a 4:3:3 hexane/CH2Cl2/(i-Pr)2O mixture, as the eluant (6 runs). Extraction of the two slower moving bands afforded pure 3-(dibenzoylmethyl)-D-glucal derivative (–)-3.22 (0.012 g, 26% yield) and 2,5- dihydropyrrole derivative (+)-3.21 (0.021 g , 45% yield .

Reaction of mono-debenzoylation of 3-(dibenzoylmethyl)-D-glucal derivative (–)-3.22

A solution of 3-(dibenzoylmethyl)-D-glucal derivative (–)-3.22 (0.020 g, 0.0385 mmol) in dry toluene (0.2 mL) was treated at room temperature with t-BuOK (0.0065 g, 0.058 mmol, 1.5 equiv) and the reaction mixture was stirred 48 h at the same temperature.

Evaporation of the filtered organic solution afforded 6-O-benzyl-3,4-dideoxy-4-(N- mesylamino)-3-(benzoylmethyl)-D-glucal [(–)-3.25] (0.013 g, 81% yield), pure as an oil:

BnO O

CH(COPh)₂ MsHN

(–)-3.22

t-BuOK O

BnO

CH₂COPh MsHN

(–)-3.25

Rf = 0.42 (1:1 hexane/AcOEt); ^[α] 20

D –14.0 (c 0.14, CHCl3). FTIR (neat)  3436, 1685, 1666, 1449, 1384, 1265, 1151, 1072, 899 cm^-1; ¹H NMR (CDCl3)  7.92-8.02 (m, 2H), 7.41-7.59 (m, 3H), 7.28-7.38 (m, 5H), 6.36 (dd, 1H, J = 6.4, 1.9 Hz), 4.66 (d, 1H, J = 11.8 Hz), 4.59 (d, 1H, J = 11.8 Hz), 4.60-4.71 (m, 2H), 4.49 (d, 1H, J = 8.4 Hz), 3.86-3.96 (m, 2H), 3.78-3.84 (m, 1H), 3.62-3.75 (m, 1H), 3.48-3.60 (m, 1H), 2.98-3.06 (m, 1H), 2.98 (s, 3H). ¹³C NMR (CDCl3) 189.1, 143.5, 139.2, 138.7, 128.9, 128.7, 128.3, 127.9, 104.7, 74.3, 69.2, 53.6, 42.0, 41.9, 36.1, 30.0. Anal. Calcd for C22H25NO5S: C, 63.60; H, 6.06; N, 3.37. Found: C, 63.51; H, 5.98; N, 3.14.

Reaction of mono-debenzoylation of 2-(dibenzoylmethyl)-2,5-dihydropyrrole derivative (+)-3.21

A solution of 2-(dibenzoylmethyl)-2,5-dihydropyrrole derivative (+)-3.21 (0.020 g, 0.0385 mmol) in dry toluene (0.2 mL) was treated at room temperature with t-BuOK (0.0065 g, 0.058 mmol, 1.5 equiv) and the reaction mixture was stirred 48 h at the same temperature. Evaporation of the filtered organic solution afforded (2R,5S,6S)-5-[2- (benzyloxy)-1-hydroxy-ethyl]-2-(benzoylmethyl)-1-mesyl-2,5-dihydro-1H-pyrrole [(+)-3.24] (0.011 g, 69% yield), pure as an oil: Rf = 0.37 (1:1 hexane/AcOEt); ^[α] 20

D

+12.4 (c 0.14, CHCl3). FTIR (neat)  3444, 1682, 1450, 1340, 1265, 1162, 1099, 895 cm^-

1; ¹H NMR (CDCl3)  7.88-7.94 (m, 2H), 7.49-7.57 (m, 1H), 7.38-7.47 (m, 2H), 7.24-7.37 (m, 5H), 6.06-6.11 (m, 1H), 5.77-5.83 (m, 1H), 4.82-4.91 (m, 1H), 4.56 (d, 1H, J = 12.0 Hz), 4.52 (d, 1H, J = 12.0 Hz), 4.41-4.46 (m, 1H), 3.96-4.04 (m, 1H), 3.53-3.68 (m, 2H), 3.22-3.39 (m, 2H), 2.78 (s, 3H), 2.54 (d, 1H, J = 6.3 Hz). ¹³C NMR (CDCl3)  196.2, 138.1, 136.8, 133.7, 132.0, 128.9, 128.3, 128.0, 126.3, 73.8, 72.8, 71.6, 70.5, 64.7, 46.8, 33.6. Anal. Calcd for C22H25NO5S: C, 63.60; H, 6.06; N, 3.37. Found: C, 63.24; H, 5.89;

N, 2.99.

N Ms

HC OH

(+)-3.21

t-BuOK N

Ms

CH₂COPh OH

(+)-3.24 O Ph

Ph O

BnO BnO

Reaction of N-mesyl aziridine 2.2 with K-enolate of dibenzoylmethane in dry toluene by t-BuOK, as the only base

A solution of N,O-dimesylate (+)-2.32 (0.035 g, 0.0895 mmol) in dry toluene (1.0 mL) was treated at room temperature with t- BuOK (0.025 g, 0.223 mmol, 2.5 equiv) in the presence of dibenzoylmethane (0.050 g, 0.223 mmol, 2.5 equiv). After 3 h stirring at the same temperature, the reaction mixture was partitioned between Et2O (20 mL) and brine (5 mL), and the aqueous layer was further extracted with Et2O (2 x 5 mL).

Evaporation of the combined organic extracts afforded a crude product consisting of the excess of dibenzoylmethane and 3-(dibenzoylmethyl)-D-gulal derivative (+)-20 (anti-1,2- addition product) which was subjected to flash chromatography. Elution with a 1:1 hexane/AcOEt mixture afforded 6-O-benzyl-3,4-dideoxy-4-(N-mesylamino)-3- (dibenzoylmethyl)-D-gulal [(+)-3.26] (0.037 g, 79% yield , pure as an oil: R  f = 0.30 (1:1 hexane/AcOEt); ^[α] 20

D +26.3 (c 1.84, CHCl3). FTIR (neat)  3450, 1679, 1665, 1450, 1389, 1259, 1148, 1070, 891 cm^-1; ¹H NMR (CDCl3)  7.90-8.03 (m, 2H), 7.77-7.87 (m, 2H), 7.56-7.67 (m, 1H), 7.44-7.55 (m, 5H), 7.27-7.39 (m, 5H), 6.47 (d, 1H, J = 6.2 Hz), 5.30 (d, 1H J = 10.6 Hz), 4.75 (d, 1H, J = 9.9 Hz), 4.57 (d, 1H, J = 11.7 Hz), 4.52 (d, 1H, J = 11.7 Hz), 4.43-4.50 (m, 1H), 4.10-4.17 (m, 1H), 3.81 (dd, 1H, J = 10.2, 6.6 Hz), 3.71 (dd, 1H, J = 10.2, 4.5 Hz), 3.60-3.65 (m, 1H), 3.32-3.44 (m, 1H), 3.36 (s, 3H). ¹³C NMR (CDCl3) 194.2, 193.3, 146.0, 137.8, 136.5, 136.1, 134.3, 129.3, 129.1, 128.8, 128.6, 128.3, 128.0, 99.0, 74.1, 73.4, 70.5, 61.6, 60.6, 50.2, 42.2, 39.6. Anal. Calcd for C29H29NO6S: C, 67.03; H, 5.63; N, 2.70. Found: C, 67.10; H, 5.39; N, 2.51.

Reaction of mono-debenzoylation of 3-(dibenzoylmethyl)-D-gulal derivative (+)-3.26

A solution of 3-(dibenzoylmethyl)-D-gulal derivative (+)-3.26 (0.020 g, 0.0385

BnO O

MsHN

CH(COPh)₂ (+)-3.26

BnO O

MsHN

CH(COPh)₂

(-)-3.27 BnO O

MsHN

CH₂COPh (+)-3.26

t-BuOK toluene

mmol) in dry toluene (0.2 mL) was treated at room temperature with t-BuOK (0.0065 g, 0.0578 mmol, 1.5 equiv) and the reaction mixture was stirred 48 h at the same temperature. Evaporation of the filtered organic solution afforded 6-O-benzyl-3,4- dideoxy-4-(N-mesylamino)-3-(benzoylmethyl)-D-gulal [(–)-3.27] (0.012 g, 75% yield), pure as an oil: Rf = 0.38 (1:1 hexane/AcOEt); ^[α] 20

D –27.6 (c 0.39, CHCl3). FTIR (neat)  3369, 1681, 1551, 1422, 1331, 1265, 1155, 1091, 896 cm^-1; ¹H NMR (CDCl3) 7.89-8.02 (m, 2H), 7.54-7.65 (m, 1H), 7.42-7.53 (m, 2H), 7.28-7.36 (m, 5H), 6.48 (d, 1H, J = 6.2 Hz), 4.77 (t, 1H, J = 6.2 Hz), 4.57 (s, 2H), 4.00 (t, 1H, J = 6.5 Hz), 3.67-3.82 (m, 2H), 2.62 (m, 2H), 3.17 (s, 3H), 3.09 (d, 2H, J = 7.2 Hz), 2.80-2.91 (m, 1H). ¹³C NMR (CDCl3)

197.9, 144.5, 137.8, 136.6, 133.8, 128.9, 128.6, 128.3, 128.1, 102.0, 77.4, 74.0, 72.5, 69.9, 51.4, 41.9, 43.0. Anal. Calcd for C22H25NO5S: C, 63.60; H, 6.06; N, 3.37. Found: C, 63.41; H, 5.79; N, 3.11.

Reaction of N-mesyl aziridine 2.2(obtained by cyclization of 2.32 with t-BuOK) with Li-enolate of dibenzoylmethane (t-BuOLi, as the base) in dry THF

A solution of dibenzoylmethane (0.12 g, 0.537 mmol, 3 equiv) in dry THF (3.6 mL) was treated with t-BuOLi (0.043 g, 0.537 mmol, 3 equiv). After 1 h stirring at room temperature, t-BuOK (0.026 g, 0.192 mmol, 1.3 equiv) was added, immediately followed by a solution of trans N,O-dimesylate (+)-2.32 (0.070 g, 0.179 mmol) in dry THF (0.6 mL) and the resulting reaction mixture was stirred at the same temperature for 18 h. The final reaction mixture was partitioned between Et2O (25 mL) and brine (7 mL), and the aqueous layer was further extracted with Et2O (2 x 7 mL). Evaporation of the combined organic extracts afforded a crude product consisting of the excess of dibenzoylmethane and of a 66:34 mixture of 2-(dibenzoylmethyl)-substituted 2,5-dihydropyrrole (+)-3.21 and the corresponding 2-(benzoylmethyl)-derivative (+)-3.24 (¹H NMR), which was subjected to flash chromatography. Elution with a 6:4 hexane/AcOEt mixture afforded

(+)-3.21 N Ms

CH(COPh)2

BnO

OH N

Ms

CH₂COPh OH

(+)-3.24 BnO

pure 2-(dibenzoylmethyl)-2,5-dihydropyrrole (+)-3.21 (0.047 g, 51% yield and 2- (benzoylmethyl)-2,5-dihydropyrrole (+)-3.24 (0.014 g, 18% yield .

Reaction of N-mesyl aziridine 2.2 (obtained by cyclization of 2.32 with t-BuOK) with Li-enolate of dibenzoylmethane (t-BuOLi, as the base) in dry THF

A solution of dibenzoylmethane (0.060 g, 0.268 mmol, 3 equiv) in dry THF (1.8 mL) was treated with t-BuOLi (0.021 g, 0.268 mmol, 3 equiv). After 1 h stirring at room temperature, t-BuOK (0.013 g, 0.116 mmol, 1.3 equiv) was added, immediately followed by a solution of trans N,O-dimesylate (+)-2.32 (0.035 g, 0.0895 mmol) in dry THF (0.3 mL) and the resulting reaction mixture was stirred at the same temperature for 18 h. The final reaction mixture was partitioned between Et2O (25 mL) and brine (7 mL), and the aqueous layer was further extracted with Et2O (2 x 7 mL). Evaporation of the combined organic extracts afforded a crude product consisting of the excess of dibenzoylmethane and of a 58:42 mixture of 3-(benzoylmethyl)-D-gulal derivative (–)-3.27 and the corresponding 2-(benzoylmethyl)-2,5-dihydropyrrole (–)-3.29 (¹H NMR), which was subjected to flash chromatography. Elution with a 6:4 hexane/AcOEt mixture afforded pure 3-(benzoylmethyl)-D-gulal derivative (–)-3.27 (0.017 g, 45% yield and  (2S,5R,6S)- 5-[2-(benzyloxy)-1-hydroxy-ethyl]-2-(benzoylmethyl)-1-mesyl-2,5-dihydro-1H- pyrrole [(–)-3.29] (0.010 g, 27% yield , an oil: R f = 0.25 (1:1 hexane/AcOEt); [α] 20

D –

16.1 (c 0.28, CHCl3). FTIR (neat)  3490, 1681, 1450, 1338, 1264, 1162, 1098, 893 cm^-1;

1H NMR (CDCl3) 7.89-7.95 (m, 2H), 7.45-7.59 (m, 3H), 7.27-7.40 (m, 5H), 6.10 (dt, 1H, J = 6.3, 2.1 Hz), 5.78 (dt, 1H, J = 6.3, 2.1 Hz), 4.88-4.96 (m, 1H), 4.63 (d, 1H, J = 11.8 Hz), 4.53 (d, 1H, J = 11.8 Hz), 4.46-4.52 (m,1H), 3.98 (dd, 1H, J = 5.9, 0.9 Hz), 3.78-3.87 (m, 1H), 3.63-3.77 (m, 2H), 3.54 (dd, 1H, J = 10.0, 5.9 Hz), 2.83 (s, 3H). ¹³C NMR (CDCl3) 198.3, 136.9, 136.6, 133.7, 132.6, 131.5, 128.9, 128.7, 128.3, 128.2, 127.4, 126.8, 73.9, 73.5, 71.3, 70.1, 65.2, 47.0, 33.5. Anal. Calcd for C22H25NO5S: C,

(-)-3.27 BnO O

MsHN

CH₂COPh

N Ms

CH₂COPh BnO

OH

(-)-3.29