Iron-Catalyzed Dealkylation of N-Alkylsulfoximines
139.6, 134.1, 133.3, 130.0, 129.9, 129.1, 127.5, 44.3, 21.4 ppm. MS
(EI, 70 eV): m/z (%) = 274 (25) [M + H]+, 273 (100) [M]+, 132 (37),
119 (70), 91 (16).
a period of 10 min. After stirring of the reaction mixture at –78 °C
for 30 min, benzyl bromide (1.48 mL, 12.42 mmol, 1.05 equiv.) was
added dropwise over a period of 30 min, and the reaction mixture
was stirred at room temperature for 12 h. The reaction was then
quenched by the addition of H2O and extracted with dichlorometh-
ane (3ϫ 20 mL). The organic layer was dried with anhydrous so-
dium sulfate. The solvent was removed under reduced pressure to
afford the product, which was purified by silica gel column
chromatography with pentane/ethyl acetate (2:1) as eluent to afford
the title compound as a pale-yellow oil (3.00 g, 11.56 mmol, 98%).
1H NMR (600 MHz, CDCl3): δ = 7.88 (dd, J = 5.4, 3.5 Hz, 2 H),
7.64–7.59 (m, 1 H), 7.59–7.55 (m, 2 H), 7.26–7.21 (m, 1 H), 7.17
(t, J = 7.3 Hz, 1 H), 7.10 (d, J = 7.1 Hz, 2 H), 3.44 (ddd, J = 13.7,
12.4, 5.0 Hz, 1 H), 3.33 (ddd, J = 13.8, 12.2, 4.9 Hz, 1 H), 3.19–
3.04 (m, 1 H), 3.04–2.90 (m, 1 H), 2.71 (s, 3 H) ppm. 13C NMR
(150 MHz, CDCl3): δ = 138.1, 137.9, 133.3, 129.8, 129.7, 129.1,
S-Methyl-N-(2-methylbenzoyl)-S-phenylsulfoximine (3t):[6d] General
Procedure 3 was applied by using N,S-dimethyl-S-phenylsulfox-
imine (2a; 85 mg, 0.5 mmol) and 2-methylbenzaldehyde (120 mg,
1.0 mmol). Silica gel column chromatography with pentane/ethyl
acetate (2:1) as eluent afforded the title compound as a white solid
(25 mg, 0.09 mmol, 18%). M.p. 108.8–109.6 °C. 1H NMR
(600 MHz, CDCl3): δ = 8.09–8.03 (m, 3 H), 7.68 (t, J = 7.4 Hz, 1
H), 7.61 (t, J = 7.7 Hz, 2 H), 7.33 (td, J = 7.5, 1.3 Hz, 1 H), 7.24–
7.18 (m, 2 H), 3.42 (s, 3 H), 2.59 (s, 3 H) ppm. 13C NMR
(150 MHz, CDCl3): δ = 177.1, 139.7, 139.5, 135.7, 134.1, 131.9,
131.3, 130.9, 130.0, 127.5, 125.7, 44.4, 21.5 ppm. MS (EI, 70 eV):
m/z (%) = 273 (8) [M]+, 210 (25), 182 (20), 156 (16),124 (23), 119
(20), 118 (100), 94 (15), 91 (19) 77 (13).
128.7, 127.1, 57.6, 29.3, 28.6 ppm. FTIR (neat): ν = 3030 (w), 2949
˜
N-(3-Methoxybenzoyl)-S-methyl-S-phenylsulfoximine (3u):[6d] Gene-
ral Procedure 3 was applied by using N,S-dimethyl-S-phenylsulfox-
imine (2a; 85 mg, 0.5 mmol) and 3-methoxybenzaldehyde (136 mg,
1.0 mmol). Silica gel column chromatography with pentane/ethyl
acetate (2:1) as eluent afforded the title compound as a white solid
(48 mg, 0.17 mmol, 33%). M.p. 90.8–92.1 °C. 1H NMR (400 MHz,
CDCl3): δ = 8.08–8.02 (m, 2 H), 7.81–7.77 (m, 1 H), 7.71–7.66 (m,
2 H), 7.64–7.58 (m, 2 H), 7.32 (t, J = 7.9 Hz, 1 H), 7.06 (ddd, J =
8.2, 2.7, 1.0 Hz, 1 H), 3.83 (s, 3 H), 3.45 (s, 3 H) ppm. 13C NMR
(150 MHz, CDCl3): δ = 174.7, 160.0, 139.4, 137.4, 134.2, 130.1,
129.4, 127.5, 122.3, 119.0, 114.0, 55.3, 44.2 ppm. MS (EI, 70 eV):
m/z (%) = 290 (61) [M + H]+, 289 (58) [M]+, 274 (22), 182 (80),
156 (100), 135 (31), 134 (82), 125 (14), 107 (14), 94 (61), 77 (38),
65 (13).
N-(3-Chlorobenzoyl)-S-methyl-S-phenylsulfoximine (3v):[8f] General
Procedure 3 was applied by using N,S-dimethyl-S-phenylsulfox-
imine (2a; 85 mg, 0.5 mmol) and 3-chlorobenzaldehyde (141 mg,
1.0 mmol). Silica gel column chromatography with pentane/ethyl
acetate (2:1) as eluent afforded the title compound as a white solid
(31 mg, 0.11 mmol, 21%). M.p. 110.8–111.9 °C. 1H NMR
(600 MHz, CDCl3): δ = 8.15 (s, 1 H), 8.04 (t, J = 7.9 Hz, 3 H),
7.70 (t, J = 7.4 Hz, 1 H), 7.62 (t, J = 7.7 Hz, 2 H), 7.50–7.45 (m,
1 H), 7.34 (t, J = 7.8 Hz, 1 H), 3.46 (s, 3 H) ppm. 13C NMR
(150 MHz, CDCl3): δ = 173.4, 139.1, 137.8, 134.5, 134.3, 132.5,
130.1, 129.9, 129.7, 127.8, 127.5, 44.3 ppm. MS (EI, 70 eV): m/z
(%) = 295 (12) [M + H]+, 294 (78) [M]+, 182 (30), 156 (33), 94 (23),
77 (10).
N-(2-Chlorobenzoyl)-S-methyl-S-phenylsulfoximine (3w):[16] General
Procedure 3 was applied by using N,S-dimethyl-S-phenylsulfox-
imine (2a; 85 mg, 0.5 mmol) and 2-chlorobenzaldehyde (141 mg,
1.0 mmol). Silica gel column chromatography with pentane/ethyl
acetate (2:1) as eluent afforded the title compound as a white solid
(21 mg, 0.07 mmol, 14%). M.p. 93.8–95.1 °C. 1H NMR (600 MHz,
CDCl3): δ = 8.10 (dd, J = 8.4, 0.9 Hz, 2 H), 7.84 (dd, J = 7.6,
1.7 Hz, 1 H), 7.69 (t, J = 7.4 Hz, 1 H), 7.62 (t, J = 7.7 Hz, 2 H),
7.40 (dd, J = 7.9, 1.0 Hz, 1 H), 7.33 (td, J = 7.7, 1.8 Hz, 1 H), 7.28
(td, J = 7.5, 1.2 Hz, 1 H), 3.47 (s, 3 H) ppm. 13C NMR (150 MHz,
CDCl3): δ = 175.0, 138.9, 136.7, 134.4, 132.6, 131.6, 131.2, 130.9,
130.1, 127.6, 126.9, 44.2 ppm. MS (EI, 70 eV): m/z (%) = 295 (18)
[M + H]+, 294 (100) [M]+, 280 (20), 278 (22), 244 (22), 182 (60),
156 (71), 140 (35), 139 (16), 138 (25), 125 (26), 111 (11), 94 (29),
77 (14).
(m), 2808 (w), 2324 (w), 2103 (w), 1740 (w), 1599 (m), 1448 (m),
1238 (s), 1146 (s), 963 (m), 842 (s), 745 (s), 692 (s) cm–1. MS (EI,
70 eV): m/z (%) = 260 (37) [M + H]+, 155 (24), 134 (47), 125 (25),
107 (100), 106 (27), 105 (75), 104 (41), 103 (17), 91 (10), 79 (25),
78 (24), 77 (49), 51 (20). HRMS: calcd. for [C15H17NOS + Na]+
282.0923; found 282.0923.
N-Acetyl-S-phenethyl-S-phenylsulfoximine (7): General Procedure 2
was applied by using N-methyl-S-phenethyl-S-phenylsulfoximine
(6; 129 mg, 0.5 mmol) and acetic anhydride (102 mg, 1.0 mmol).
Silica gel column chromatography with pentane/ethyl acetate (2:1)
as eluent afforded the title compound as a clear colorless oil
1
(80 mg, 0.28 mmol, 55%). H NMR (400 MHz, CDCl3): δ = 8.00–
7.94 (m, 2 H), 7.70–7.65 (m, 1 H), 7.63–7.56 (m, 2 H), 7.28–7.17
(m, 4 H), 7.12–7.05 (m, 2 H), 3.70 (dddd, J = 56.3, 13.9, 11.7,
5.1 Hz, 2 H), 2.98 (dddd, J = 64.4, 13.8, 11.8, 5.1 Hz, 2 H), 2.16
(s, 3 H) ppm. 13C NMR (100 MHz, CDCl3): δ = 180.3, 137.0,
136.9, 133.9, 129.7, 128.9, 128.4, 127.9, 127.1, 56.8, 28.6, 26.9 ppm.
FTIR (neat): ν = 3038 (w), 2932 (w), 1737 (w), 1636 (s), 1451 (m),
˜
1359 (m), 1217 (s), 1142 (s), 1031 (s), 839 (m), 749 (s), 687 (m)
cm–1. MS (EI, 70 eV): m/z (%) = 288 (13) [M + H]+, 287 (6) [M]+,
183 (13), 125 (17), 107 (19), 106 (12), 105 (100), 104 (40), 94 (14),
91 (11), 79 (19), 78 (12), 77 (40), 51 (15). HRMS: calcd. for
[C16H17NO2S + Na]+ 310.0872; found 310.0872.
NH-S-Phenethyl-S-phenylsulfoximine (8): A solution of N-acetyl-S-
phenethyl-S-phenylsulfoximine (7; 144 mg, 0.5 mmol, 1.0 equiv.) in
concentrated HCl (5 mL) was stirred at 80 °C for 16 h. The reaction
mixture was made basic by the addition of 4 m NaOH, and the
aqueous layer was extracted with dichloromethane (2ϫ 20 mL).
The combined organic layers were then dried with an-
hydrous magnesium sulfate. The solvent was removed under re-
duced pressure to afford the product, which was further purified
by silica gel column chromatography with pentane/ethyl acetate
(1:1) as eluent to afford the title compound as a clear oil (120 mg,
1
0.49 mmol, 98%). H NMR (400 MHz, CDCl3): δ = 8.00 (dd, J =
5.3, 3.3 Hz, 2 H), 7.66–7.59 (m, 1 H), 7.59–7.52 (m, 2 H), 7.29–
7.22 (m, 2 H), 7.22–7.16 (m, 1 H), 7.14–7.08 (m, 2 H), 3.41 (qdd,
J = 13.7, 11.0, 5.7 Hz, 2 H), 3.05 (qdd, J = 13.8, 11.0, 6.0 Hz, 2
H), 2.50 (s, 1 H) ppm. 13C NMR (100 MHz, CDCl3): δ = 142.4,
138.1, 133.5, 129.6, 129.1, 128.8, 128.7, 127.2, 58.7, 29.0 ppm.
FTIR (neat): ν = 3557 (w), 3271 (m), 3060 (w), 2927 (w), 2327 (w),
˜
2080 (w), 1600 (w), 1493 (m), 1446 (s), 1405 (m), 1216 (s), 1084 (s),
981 (s), 745 (s), 695 (s) cm–1. MS (EI, 70 eV): m/z (%) = 246 (100)
[M + H]+, 217 (12), 182 (8), 120 (6), 105 (13), 104 (23), 103 (5),
N-Methyl-S-phenethyl-S-phenylsulfoximine (6): n-Butyllithium
(1.6 m in hexane, 12.42 mmol, 1.05 equiv.) was slowly added to a
solution of N,S-dimethyl-S-phenylsulfoximine (2a; 2.0 g, 77 (12). HRMS: calcd. for [C14H15NOS + Na]+ 268.0767; found
11.84 mmol) in dry tetrahydrofuran (15 mL, 0.8 m) at –78 °C over
268.0760.
Eur. J. Org. Chem. 2015, 5594–5602
© 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
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