4H), 2.90–2.85 (m, 2H). 13C NMR: d 140.4, 139.4, 132.8, 129.3, 128.9, 128.6, 128.2, 125.9, 45.8, 45.1, 39.4. HRMS calcd for C15H18NOS: 260.1109, found: 260.1107.
Ethyl 2-[[methyl(oxo)phenyl-.6-sulfanylidene]amino]-3-phenylpropanoate (5e). Isolated as a mixture of diastereomers in 2:3 ratio; colorless oil; yield 41%. 1H NMR: d 7.91–7.89 (m, 1H), 7.60–7.50 (m, 2H), 7.32–7.17 (m, 7H), 4.20–3.60 (m, 3H), 3.20–2.90 (m, 5H), 1.23 (t, J= 7.2 Hz, 0.4×3H, diastereomer 1), 1.02 (t, J = 7.1 Hz, 0.6×3H, diastereomer 2). 13C NMR: d 173.6 (172.8), 138.3 (137.8), 133.0 (132.7), 129.9, 129.6, 129.2, 129.1, 128.5, 128.4, 128.1, 126.1, 60.8 (60.4), 59.4 (58.3), 45.2 (45.1), 42.3 (41.4), 14.0 (13.9). Anal. Calcd for C18H21NO3S: C, 65.23; H, 6.39; N, 4.23. Found: C, 65.41; H, 6.52; N, 4.49.
[(4-Chlorobenzyl)imino](oxo)diphenyl-.6-sulfane (5f). Colorless oil; yield 62%. 1H NMR: d 8.01–7.98 (m, 4H), 7.53–7.45 (m, 6H), 7.38 (d, J = 8.4 Hz, 2H), 7.28 (d, J = 8.5 Hz, 2H), 4.24 (s, 2H). 13C NMR: d 140.5, 140.1, 132.5, 132.1, 129.2, 128.8, 128.5, 128.3, 46.5. Anal. Calcd for C19H16ClNOS: C, 66.76; H, 4.72. Found: C, 66.39; H, 4.96.
(Benzylimino)(oxo)diphenyl-.6-sulfane (5g).18 Colorless oil; yield 49%. 1H NMR: d 8.03-8.00 (m, 4H), 7.53-7.44 (m, 8H), 7.32 (t, J = 7.1 Hz, 2H), 7.25-7.19 (m, 1H), 4.28 (s, 2H). 13C NMR: d 141.5, 140.7, 132.4, 129.1, 128.6, 128.2, 127.4, 126.4, 47.1. Anal. Calcd for C19H17NOS: C, 74.23; H, 5.57; N, 4.56. Found: C, 74.13; H, 5.59; N, 4.62.
[(Mesitylmethyl)imino](oxo)diphenyl-.6-sulfane (5h). White microcrystals (from ethyl acetate/hexanes); mp 97 °C; yield 53%. 1H NMR: d 7.96-7.93 (m, 4H), 7.48-7.42 (m, 6H), 6.78 (s, 2H), 4.20 (s, 2H), 2.35 (s, 6H), 2.23 (s, 3H). 13C NMR: d 141.3, 136.9, 136.1, 134.5, 132.1, 128.9, 128.8, 128.3, 40.7, 20.8, 19.6. Anal. Calcd for C22H23NOS: C, 75.61; H, 6.63; N, 4.01. Found: C, 75.29; H, 6.75; N, 4.01.
General procedure for the nucleophilic substitution of 3a-e with allyl(trimethyl)silanes
To a mixture of N-(benzotriazol-1-ylalkyl)sulfoximine 3 (1 mmol) and allyl(trimethyl)silane (1 mmol) in CH2Cl2 (20 mL) was added BF3•Et2O (2 mmol) at 0 °C. The reaction mixture was stirred at 0 °C for 2 h and then at room temperature for 18 h. The reaction was quenched by aqueous NaHCO3 solution and extracted with CH2Cl2. The combined solvent extract was dried over anhydrous Na2SO4 and removed in vacuo. The residue was purified by column chromatography with hexanes/ethyl acetate (2:1) as eluent to give the desired N-substituted sulfoximine 5.
Ethyl 2-[[methyl(oxo)phenyl-.6-sulfanylidene]amino]-4-pentenoate (5i). Isolated as a 1:1 mixture of diastereomers; colorless oil; yield 64%. 1H NMR: d 7.96–7.92 (m, 2H), 7.67–7.52 (m, 3H), 5.93–5.70 (m, 1H), 5.13–5.02 (m, 2H), 4.18 (q, J = 7.1 Hz, 0.5×2H, diastereomer 1), 4.12– 3.91 (m, 0.5×2H, diastereomer 2), 3.76 (t, J = 6.5 Hz, 0.5×1H, diastereomer 1), 3.69 (t, J = 6.7 Hz, 0.5×1H, diastereomer 2), 3.15 (s, 3H), 2.64–2.40 (m, 2H), 1.27 (t, J = 7.1 Hz, 0.5×3H, diastereomer 1), 1.15 (t, J = 7.1 Hz, 0.5×3H, diastereomer 2). 13C NMR: d 173.2, 172.7 (other diastereomer), 139.7, 139.4 (other diastereomer), 134.1, 134.0 (other diastereomer), 132.9, 129.2, 128.5, 128.3 (other diastereomer), 117.4, 117.3 (other diastereomer), 60.5, 60.3 (other diastereomer), 56.9, 56.4 (other diastereomer), 45.4, 45.0 (other diastereomer), 40.4, 39.5 (other
