3.3. General Procedure for the Synthesis of Cyclic Sulfamidates

The synthesis of S,S-dioxides was performed according to a modified literature procedure [39,40]. To a solution of amino alcohol 1 or 5 (1 mmol) and triethylamine (3 mmol, 0.42 mL) in dry dichloromethane (3.5 mL) was added a solution of thionyl chloride (0.8 mmol, 58 μL) in dry dichloromethane (0.25 mL) at −78 °C over 20 min. The mixture was stirred at −78 °C for 20 min and at 0 °C for the next 20 min. The reaction mixture was partitioned between ether and water, the organic layer was washed with brine and dried over anhydrous sodium sulfate, filtered and the filtrate was concentrated in vacuo. The residue was dissolved in acetonitrile (4 mL), cooled to 0 °C and NaIO₄ (1.2 mmol, 257 mg), RuCl₃ · 3H₂0 (ca. 2 mg) and water (10 μL) were added. The reaction mixture was stirred at room temperature for 1 h, then diluted with water and extracted 3 × Et₂O. The combined organic extracts were washed with brine and dried over sodium sulfate. The residue was purified by column chromatography (SiO₂, 10% AcOEt in hexane) to provide the cyclic sulfamidate.

(5S)-Phenyl-3-[(S)-1-phenylethyl]-1,2,3-oxathiazolidine-2,2-dioxide (5S,1′S)-17: White solid, 151 mg, 50%, m.p. 100–101 °C, [α]D20 = −73 (c = 0.62 CHCl₃), ¹H-NMR (400 MHz, CDCl₃) δ: 7.39–7.33 (m, 10H), 5.62 (dd, J = 10.1, 6.1 Hz, 1H), 4.35 (q, J = 6.4 Hz, 1H), 3.40 (dd, J = 10.1, 6.1 Hz, 1H), 3.19 (t, J = 9.8 Hz, 1H), 1.75 (d, J = 6.7 Hz, 3H); ¹³C-NMR (101 MHz, CDCl₃) δ: 140.7, 134.7, 129.9, 129.1, 129.0, 128.6, 127.1, 126.5, 80.9, 59.1, 55.3, 20.8, HR-MS (ESI) [C₁₆H₁₇NO₃S + Na]⁺ requires 326.0822; found 326.0826.

(4S,5S)-4-Phenyl-5-(pyridin-2-yl)-3-[(S)-1-phenylethyl]-1,2,3-oxathiazolidine-2,2-dioxide (4S,5S,1′S)-18: White solid, 288 mg, 76%, m.p. 68–70 °C, [α]D20 = −11 (c = 0.73 CHCl₃), ¹H-NMR (400 MHz, CDCl₃) δ: 8.32 (d, J = 4.9 Hz, 1H), 7.36–7.26 (m, 6H), 7.03–6.94 (m, 7H), 5.97 (d, J = 6.1 Hz, 1H), 4.96 (q, J = 6.7 Hz, 1H), 4.75 (d, J = 6.4 Hz, 1H), 1.50 (d, J = 6.7 Hz, 3H); ¹³C-NMR (101 MHz, CDCl₃) δ: 152.6, 148.7, 138.5, 136.5, 136.1, 128.7, 128.6, 128.1, 128.0, 127.9, 126.9, 123.1, 120.9, 83.1, 65.8, 56.4, 20.2; HR-MS (ESI) [C₂₁H₂₀N₂O₃S + Na]⁺ requires 403.1087; found 403.1084.

(4R,5R)-4-Phenyl-5-(pyridin-2-yl)-3-[(S)-1-phenylethyl]-1,2,3-oxathiazolidine-2,2-dioxide (4R,5R,1′S)-18: White solid, 296 mg, 79%, [α]D20 = −7 (c = 0.89 CHCl₃), ¹H-NMR (400 MHz, CDCl₃) δ: 8.32 (d, J = 4.9 Hz, 1H), 7.37 (td, J = 7.6, 1.5 Hz, 1H), 7.28–7.21 (m, 5H), 7.01–6.97 (m, 7H), 6.08 (d, J = 6.1 Hz, 1H), 4.82 (d, J = 6.1 Hz, 1H), 4.33 (q, J = 6.7 Hz, 1H), 1.85 (d, J = 7.0 Hz, 3H); ¹³C-NMR (101 MHz, CDCl₃) δ: 152.7, 148.7, 140.5, 136.6, 133.5, 128.9, 128.4, 128.33, 128.32, 128.2, 127.2, 123.2, 120.7, 82.5, 67.2, 57.0, 20.1; HR-MS (ESI) [C₂₁H₂₀N₂O₃S + H]⁺ requires 381.1261; found 381.1265.