The Journal of Organic Chemistry
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177.7; m/z (DIP) 309 (M+, <1%), 253 (37), 207 (51), 206 (12), 205
(2H, q, J = 7.1 Hz), 7.39−7.52 (3H, m), 7.92 (2H, d, J = 6.5 Hz); 13
C
(95), 162 (19), 160 (18), 159 (14), 132 (100), 57 (23); HRMS M+
NMR (75 MHz, CDCl3) δ 14.2, 22.7, 23.8, 31.6, 33.7, 57.7, 60.4,
127.5, 128.6, 131.6, 137.6, 173.0, 178.8; m/z (DIP) 323 (M+, <1%),
267 (15), 221 (21), 220 (14), 219 (94), 145 (18), 144 (19), 132
(100), 104 (19), 103 (21), 77 (15), 57 (35); HRMS M+ − C4H8
found 309.1393, C16H23NO3S requires 309.1399. For ent-2a, [α]20
D
+6.1 (c 1.5, CH2Cl2).
Ethyl 4-[(R)-tert-Butylsulfinylimino]-4-(4-methoxyphenyl)-
butanoate (2b). Yellow oil; Rf 0.47 (hexane/ethyl acetate 1/1);
[α]20D +32.0 (c 1.6, CH2Cl2); IR (neat) 3055, 1730, 1587, 1254, 1174,
found 267.0936, C13H17NO3S requires 267.0929. For ent-2g, [α]20
D
+10.5 (c 1.0, CH2Cl2).
1
1076 cm−1; H NMR (300 MHz, CDCl3) δ 1.24 (3H, t, J = 7.1 Hz),
Ethyl 5-[(R)-tert-Butylsulfinylimino]-5-(4-methoxyphenyl)-
pentanoate (2h). Yellow oil; Rf 0.26 (hexane/ethyl acetate 3/1);
[α]20D +19.0 (c 1.1, CH2Cl2); IR (neat) 3068, 1729, 1606, 1586, 1254,
1174, 1067 cm−1; 1H NMR (400 MHz, CDCl3) δ 1.27 (3H, t, J = 7.1
Hz), 1.32 (9H, s), 1.95−2.04 (2H, m), 2.46 (2H, t, J = 7.1 Hz), 3.03−
3.40 (2H, m), 3.86 (3H, s), 4.15 (2H, q, J = 7.1 Hz), 6.93 (2H, d, J =
9.0 Hz), 7.93 (2H, br d, apparent J = 7.8 Hz); 13C NMR (100 MHz,
CDCl3) δ 14.2, 22.6, 24.0, 31.6, 33.7, 55.4, 57.3, 60.4, 113.8, 129.5,
130.1, 162.5, 173.1, 178.3; m/z (DIP) 353 (M+, <1%), 297 (29), 249
(61), 175 (30), 163 (20), 162 (100), 161 (20), 149 (18), 135 (34),
134 (21), 133 (18), 57 (20); HRMS M+ − C4H8 found 297.1040,
1.31 (9H, s), 2.53−2.84 (2H, m), 3.34−3.61 (2H, m), 3.86 (3H, s),
4.13 (2H, q, J = 7.1 Hz), 6.93 (2H, d, J = 9.0 Hz), 7.70−8.01 (2H, br
s); 13C NMR (75 MHz, CDCl3) δ 14.1, 22.5, 27.6, 33.1, 55.4, 57.4,
60.8, 113.9, 129.4, 129.7, 162.5, 172.0, 177.1; m/z (DIP) 339 (M+,
<1%), 283 (41), 237 (28), 235 (55), 190 (17), 189 (30), 163 (23),
162 (100), 147 (18), 134 (39), 133 (21), 57 (31); HRMS M+ − C4H8
found 283.0888, C13H17NO4S requires 283.0878. For ent-2b, [α]20
D
−32.5 (c 1.4, CH2Cl2).
Ethyl 4-[(R)-tert-Butylsulfinylimino]-4-(4-chlorophenyl)-
butanoate (2c). Greenish oil; Rf 0.26 (hexane/ethyl acetate 3/1);
[α]20D +29.5 (c 1.1, CH2Cl2); IR (neat) 3064, 1732, 1601, 1585, 1179,
C14H19NO4S requires 297.1035. For ent-2h, [α]20 −19.0 (c 1.1,
D
1
1090 cm−1; H NMR (300 MHz, CDCl3) δ 1.24 (3H, t, J = 7.1 Hz),
CH2Cl2).
1.32 (9H, s), 2.50−2.84 (2H, m), 3.15−3.74 (2H, m), 4.13 (2H, q, J =
7.1 Hz), 7.40 (2H, d, J = 8.4 Hz), 7.63−7.90 (2H, br s); 13C NMR (75
MHz, CDCl3) δ 14.0, 22.6, 27.4, 32.7, 57.9, 60.8, 128.6, 128.8, 135.6,
137.9, 171.6, 176.3; m/z (DIP) 343 (M+, <1%), 289 (13), 287 (36),
243 (22), 241 (87), 239 (95), 168 (33), 166 (100), 137 (18), 57 (48);
HRMS M+ found 343.1018, C16H22ClNO3S requires 343.1009. For
ent-2c, [α]20 −29.0 (c 1.0, CH2Cl2).
Ethyl 5-[(R)-tert-Butylsulfinylimino]-5-(2-naphthyl)-
pentanoate (2i). Yellow oil; Rf 0.32 (hexane/ethyl acetate 4/1);
[α]20D +9.0 (c 3.0, CH2Cl2); IR (neat) 3058, 1729, 1610, 1588, 1186,
1
1068 cm−1; H NMR (400 MHz, CDCl3) δ 1.26 (3H, t, J = 7.1 Hz),
1.37 (9H, s), 2.04−2.14 (2H, m), 2.50 (2H, t, J = 7.1 Hz), 3.14−3.39,
3.40−3.60 (1H each, 2 m), 4.16 (2H, q, J = 7.1 Hz), 7.51−7.58 (2H,
m), 7.85 (2H, d, J = 8.6 Hz), 7.95 (1H, d, J = 7.3 Hz), 8.05 (1H, d, J =
7.9 Hz), 8.41 (1H, s); 13C NMR (100 MHz, CDCl3) δ 14.2, 22.7, 24.1,
31.6, 33.7, 57.7, 60.4, 124.1, 126.6, 127.4, 127.8, 128.2, 128.4, 129.3,
132.7, 134.76, 134.83, 172.9, 178.6; m/z (DIP) 373 (M+, <1%), 317
(26), 269 (100), 195 (16), 182 (22), 142 (14), 127 (29), 57 (43);
HRMS M+ − C4H8 found 317.1082, C17H19NO3S requires 317.1086.
For ent-2i, [α]20 −8.5 (c 2.0, CH2Cl2).
Ethyl 4-[D(R)-tert-Butylsulfinylimino]-4-cyclopentylbutanoate
(2d). An inseparable mixture of geometric isomers in ca. 3:1 ratio was
obtained. The following characterization data are reported for the
mixture of isomers with the relative integration for each signal: pale
yellow oil; Rf 0.34 (hexane/ethyl acetate 3/1); [α]20 −63.0 (c 1.0,
D
1
CH2Cl2); IR (neat) 1733, 1614, 1176, 1070 cm−1; H NMR (300
Ethyl 5-[(R)-Dtert-Butylsulfinylimino]-5-(2-thienyl)pentanoate
MHz, CDCl3) δ 1.16−1.29 (12.2H, m), 1.56−1.98 (8.2H, m), 2.50−
3.05 (4.4H, m), 3.60−3.81 (0.6H, m), 4.01−4.23 (2.0H, m); 13C
NMR (75 MHz, CDCl3) δ 14.1, 21.8, 22.0, 22.3, 25.5, 25.86, 25.91,
29.4, 30.3, 30.6, 30.7, 31.1, 31.5, 31.9, 45.9, 50.3, 55.9, 56.8, 60.4, 60.3,
171.9, 172.9, 188.7, 189.9; m/z (DIP) 301 (M+, <1%), 273 (30), 227
(42), 225 (100), 179 (21), 151 (26), 138 (84), 109 (21), 57 (32);
HRMS M+ − C4H8 found 245.1086, C11H19NO3S requires 245.1086.
(2j). Yellow oil; Rf 0.38 (hexane/ethyl acetate 3/1); [α]20 +99.0 (c
D
1.0, CH2Cl2); IR (neat) 3075, 1729, 1572, 1182, 1071 cm−1; 1H NMR
(400 MHz, CDCl3) δ 1.27 (3H, t, J = 7.1 Hz), 1.31 (9H, s), 2.05−2.15
(2H, m), 2.47 (2H, t, J = 6.9 Hz), 3.07−3.18, 3.22−3.32 (1H each, 2
m), 4.16 (2H, q, J = 7.1 Hz), 7.10 (1H, dd, J = 5.0, 3.8 Hz), 7.49 (1H,
dd, J = 5.0, 0.9 Hz), 7.67 (1H, dd, J = 3.8, 0.9 Hz); 13C NMR (100
MHz, CDCl3) δ 14.2, 22.5, 24.4, 32.4, 33.6, 57.8, 60.4, 128.1, 129.9,
132.1, 145.1, 173.0, 173.2; m/z (DIP) 329 (M+, <1%), 273 (33), 211
(11), 198 (13), 197 (100), 156 (17), 124 (25), 57 (30); HRMS M+ −
C4H8 found 273.0499, C11H15NO3S2 requires 273.0493. For ent-2j,
For ent-2d, [α]20 +62.0 (c 0.9, CH2Cl2).
D
Ethyl 4-[(R)-tert-Butylsulfinylimino]-4-cyclohexylbutanoate
(2e). An inseparable mixture of geometric isomers in ca. 3:1 ratio
was obtained. The following characterization data are reported for the
mixture of isomers with the relative integration for each signal: pale
[α]20 −100.0 (c 0.9, CH2Cl2).
D
yellow oil; Rf 0.26 (hexane/ethyl acetate 3/1); [α]20 −65.0 (c 0.9,
Ethyl 5-[(R)-tert-Butylsulfinylimino]-6-methylheptanoate
D
1
CH2Cl2); IR (neat) 1732, 1616, 1180, 1069 cm−1; H NMR (300
(2k). Pale yellow oil; Rf 0.44 (hexane/ethyl acetate 3/2); [α]20
D
1
MHz, CDCl3) δ 0.93−1.54 (17.1H, m), 1.64−1.92 (5.1H, m), 2.21−
2.30 (0.2H, m), 2.45−3.07 (3.7H, m), 3.25−3.50 (0.6H, m), 4.04−
4.20 (2.0H, m); 13C NMR (75 MHz, CDCl3) δ 14.1, 22.0, 22.4, 25.6,
25.8, 29.3, 29.7, 30.2, 30.5, 30.7, 32.1, 45.5, 49.6, 56.0, 56.9, 60.4, 60.8,
172.0, 172.9, 188.7, 190.7; m/z (DIP) 315 (M+, <1%), 287 (12), 259
(43), 239 (100), 193 (17), 152 (61), 57 (53); HRMS M+ − C4H8
−143.0 (c 2.2, CH2Cl2); IR (neat) 1733, 1620, 1182, 1071 cm−1; H
NMR (300 MHz, CDCl3) δ 1.08−1.19 (6H, m), 1.24 (9H, s), 1.26
(3H, t, J = 7.1 Hz), 1.85−2.00 (2H, m), 2.25−2.53 (3H, m), 2.57−
2.88 (2H, m), 4.14 (2H, q, J = 7.1 Hz); 13C NMR (75 MHz, CDCl3) δ
14.2, 20.1, 20.3, 22.3, 22.7, 33.9, 34.0, 39.1, 56.7, 60.3, 172.8, 190.8; m/
z (DIP) 289 (M+, <1%), 186 (12), 185 (100), 140 (15), 139 (42), 98
(68), 96 (21), 57 (54); HRMS M+ − C4H8SO found 185.1415,
found 259.1254, C12H21NO3S requires 259.1242. For ent-2e, [α]20
D
+66.0 (c 1.1, CH2Cl2).
C10H19NO2 requires 185.1416. For ent-2k, [α]20 +142.0 (c 2.0,
D
Ethyl 4-[(R)-tert-Butylsulfinylimino]-5-methylhexanoate (2f).
CH2Cl2).
Pale yellow oil; Rf 0.38 (hexane/ethyl acetate 7/3); [α]20 −123.5 (c
Ethyl 6-[(R)-tert-Butylsulfinylimino]-6-phenylhexanoate (2l).
D
1.9, CH2Cl2); IR (neat) 1733, 1618, 1173, 1072 cm−1; 1H NMR (300
MHz, CDCl3) δ 1.18 (6H, d, J = 6.9 Hz), 1.21 (9H, s), 1.25 (3H, t, J =
7.1 Hz), 2.51−3.05 (4H, m), 3.60−3.84 (1H, m), 4.11 (2H, t, J = 7.1
Hz); 13C NMR (75 MHz, CDCl3) δ 14.1, 19.5, 20.3, 22.0, 29.1, 29.2,
34.6, 56.0, 60.4, 172.8, 191.1; m/z (DIP) 275 (M+, <1%), 219 (14),
172 (11), 171 (100), 125 (27), 98 (38), 57 (34); HRMS M+ − C4H8
Yellow oil; Rf 0.32 (hexane/ethyl acetate 3/1); [α]20 −22.0 (c 0.9,
D
CH2Cl2); IR (neat) 3061, 1731, 1593, 1179, 1071 cm−1; H NMR
1
(400 MHz, CDCl3) δ 1.23 (3H, t, J = 7.1 Hz), 1.33 (9H, s), 1.67−1.81
(4H, m), 2.34 (2H, t, J = 7.3 Hz), 3.07−3.39 (2H, m), 4.10 (2H, q, J =
7.1 Hz), 7.40−7.50 (3H, m), 7.84 (2H, d, J = 6.7 Hz); 13C NMR (100
MHz, CDCl3) δ 14.2, 22.7, 25.0, 28.1, 32.1, 33.8, 57.5, 60.3, 127.4,
128.6, 131.5, 137.7, 173.3, 179.4; m/z (DIP) 337 (M+, <1%), 281
(15), 234 (18), 233 (100), 171 (32), 144 (22), 143 (54), 132 (92),
104 (25), 103 (21), 57 (41); HRMS M+ − C4H8 found 281.1093,
found 219.0917, C9H17NO3S requires 219.0929. For ent-2f, [α]20
D
+124.0 (c 1.0, CH2Cl2).
Ethyl 5-[(R)-tert-Butylsulfinylimino]-5-phenylpentanoate
(2g). Yellow oil; Rf 0.35 (hexane/ethyl acetate 3/1); [α]20 −10.5
C14H19NO3S requires 281.1086. For ent-2l, [α]20 +22.5 (c 1.0,
D
D
1
(c 1.1, CH2Cl2); IR (neat) 3050, 1729, 1591, 1181, 1068 cm−1; H
CH2Cl2).
NMR (300 MHz, CDCl3) δ 1.26 (3H, t, J = 7.1 Hz), 1.33 (9H, s),
1.95−2.08 (2H, m), 2.46 (2H, t, J = 7.1 Hz), 3.11−3.44 (2H, m), 4.14
Asymmetric Transfer Hydrogenation of Iminoesters 2 and
ent-2. General Procedure. A mixture of [RuCl2(p-cymene)]2 (14
3651
dx.doi.org/10.1021/jo400164y | J. Org. Chem. 2013, 78, 3647−3654