The Journal of Organic Chemistry
ARTICLE
6.30 (dd, 1H, J = 1.5, 6.0 Hz), 7.34 (d, 2H, J = 8.0 Hz), 7.70 (d, 2H, J =
8.0 Hz); 13C NMR (125 MHz, CDCl3) δ 21.7, 25.8, 29.8, 30.8, 43.2, 46.7,
59.1, 71.5, 80.1, 86.1, 128.4, 129.8, 133.0, 133.8, 136.7, 143.9, 202.2;
IR (neat) cmꢀ1 2923 m, 1709s, 1327 m, 1162s, 1095s; MS (ESI) m/e
(% relative intensity) 385.2 (10) (M þ Na þ H)þ, 384.1 (100) (M þ
Na)þ ; HRMS (ESI) m/e calcd for C19H23NO4Sþ (M þ H)þ 362.1421,
found 362.1408.
Cycloadduct 59 (25 mg, 0.065 mmol) was obtained in 97% yield as a
60:40 inseparable mixture of diastereomers from allenamide 58 accord-
ing to the general procedure. Rf = 0.50 [1:5 EtOAc/hexanes]; pale
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yellow oil; H NMR (500 MHz, CDCl3) Major δ 0.07 (s, 3H), 0.19
(s, 3H), 0.89 (s, 9H), 0.90 (s, 3H), 1.03 (s, 3H), 1.05ꢀ1.10 (m, 1H),
1.35ꢀ1.41 (m, 1H), 1.67ꢀ1.78 (m, 4H), 1.92ꢀ1.94 (m, 1H),
2.00ꢀ2.10 (m, 2H), 2.24 (td, 1H, J = 8.0, 12.8 Hz), 2.40 (d, 1H, J =
17.2 Hz), 2.95 (dd, 1H, J = 7.6, 17.2 Hz), 3.35ꢀ3.42 (m, 1H), 3.48
(d, 1H, J = 13.6 Hz), 3.59 (d, 1H, J = 13.6 Hz), 4.00ꢀ4.07 (m, 2H), 4.32
(s, 1H), 5.04 (d, 1H, J = 7.2 Hz),6.29 (d, 1H, J = 5.6 Hz), 6.46ꢀ6.48
(m, 1H); Select resonances for minor δ 0.05 (s, 3H), 0.90 (s, 3H), 0.87
(s, 9H), 0.91 (s, 3H), 1.25 (s, 3H), 2.39 (d, 1H, J = 17.6 Hz), 2.94 (dd,
1H, J = 7.6, 17.6 Hz), 3.45 (d, 1H, J = 14.0 Hz), 3.73 (d, 1H, J = 14.4
Hz), 4.17 (dd, 1H, J = 8.0, 11.6 Hz), 4.27 (s, 1H), 6.27 (d, 1H, J = 5.6
Hz); 13C NMR (125 MHz, CDCl3) not obtained for inseparable
mixture; IR (thin film) cmꢀ1 2955 m, 1737s, 1329s, 1248 m, 1099 m;
MS (ESI) m/e (% relative intensity) 519.5 (20) (M þ Na þ H)þ, 518.5
(100) (M þ Na)þ; HRMS (ESI) m/e calcd for C25H41NO5SSiþ (M þ
Na)þ 518.2367, found 518.2383.
Cycloadduct 49 (7 mg, 0.020 mmol) was obtained in 17% yield from
allenamide 48 according to the general procedure. Rf = 0.17 [1:3
EtOAc/hexanes]; colorless oil; 1H NMR (500 MHz, CDCl3) δ 1.71 (br
d, 2H, J = 14.0 Hz), 1.84ꢀ1.95 (m, 2H), 2.02 (dd, 1H, J = 6.0, 14.5 Hz),
2.22 (t, 1H, J = 14.0 Hz), 2.38 (d, 1H, J = 18.0 Hz), 2.41 (s, 3H),
2.75ꢀ2.80 (m, 1H), 3.58 (d, 1H, J = 15.0 Hz), 4.38 (s, 1H), 4.98 (d, 1H,
J = 6.5 Hz), 6.26 (d, 1H, J = 5.5 Hz), 6.33 (d, 1H, J = 6.0 Hz), 7.27 (d,
2H, J = 8.0 Hz), 7.73 (d, 2H, J = 8.0 Hz); 13C NMR (125 MHz, CDCl3)
δ 21.7, 21.8, 30.6, 33.5, 46.5, 47.3, 70.3, 76.7, 89.8, 128.1, 129.3, 133.7,
137.3, 137.5, 143.3, 205.1; IR (thin film) cmꢀ1 2926 m, 1723s, 1330s,
1265 m, 1153s; MS (ESI) m/e (% relative intensity) 371.3 (10) (M þ
Na þ H)þ, 370.3 (100) (M þ Na)þ; HRMS (ESI) m/e calcd for
C18H21NO4Sþ (M þ Na)þ 370.1084, found 370.1101.
Cycloadduct 67 (35 mg, 0.071 mmol) was obtained in 85% yield as a
4:1 mixture of diastereomers from allenamide (()-63 according to the
general procedure. Major: Rf = 0.19 [1:4 EtOAc/hexanes]; white solid;
mp = 97ꢀ98 °C; 1H NMR (500 MHz, CDCl3) δ 0.91ꢀ0.95 (m, 3H),
0.90 (d, 18H, J = 8.0 Hz), 2.39 (d, 1H, J = 15.0 Hz), 2.40 (s, 3H), 3.18
(dd, 1H, J = 5.0, 15.0 Hz), 3.33 (d, 1H, J = 11.0 Hz), 3.42 (s, 1H), 4.04
(dd, 1H, J = 4.0, 11.5 Hz), 4.30 (d, 1H, J = 4.0 Hz), 5.08 (d, 1H, J = 5.0
Hz), 6.17 (d, 1H, J = 6.0 Hz), 6.34 (d, 1H, J = 6.0 Hz), 7.31 (d, 2H, J = 8.0
Hz), 7.80 (d, 2H, J = 8.0 Hz); 13C NMR (125 MHz, CDCl3) δ 21.1, 17.9,
18.0, 21.6, 44.4, 59.3, 68.4, 72.5, 78.8, 95.7, 128.1, 128.9, 129.8, 133.5,
136.5, 143.8, 200.9; IR (neat) cmꢀ1 2944 m, 1721s, 1462 m, 1352s,
1165s; MS (ESI) m/e (% relative intensity) 515.2 (5) (M þ Na þ H)þ,
509.2 (100), 492.2 (75) (M þ H)þ; HRMS (ESI) m/e calcd for
C25H37NO5SSiþ (M þ H)þ 492.2235, found 492.2236. Minor:
Cycloadduct 51 (24 mg, 0.078 mmol) was obtained in 73% yield as a
3:1 mixture of diastereomers from allenamide 50 according to the general
procedure. Major: Rf = 0.20 [1:3 EtOAc/hexanes]; white solid; mp =
1
83ꢀ84 °C; H NMR (500 MHz, CDCl3) δ 1.67ꢀ1.72 (m, 1H), 1.99
(quintet of doublets, 1H, J = 3.0, 7.0 Hz), 2.31ꢀ2.36 (m, 1H), 2.43 (s,
3H), 2.45 (d, 1H, J = 15.0 Hz), 2.54ꢀ2.59 (m, 1H), 2.68 (d, 1H, J = 5.0
Hz) 2.70 (dd, 1H, J = 2.0, 5.0 Hz), 2.97ꢀ3.00 (m, 1H), 3.27 (q, 1H,
J = 9.0 Hz), 3.44 (td, 1H, J = 3.0, 8.0 Hz), 4.91 (d, 1H, J = 9.0 Hz), 5.48
(ddd, 1H, J = 1.0, 4.5, 11.0 Hz), 5.84 (ddd, 1H, J = 1.5, 2.5, 7.5 Hz), 7.31
(d, 2H, J = 8.5 Hz), 7.75 (d, 2H, J = 8.5 Hz); 13C NMR (125 MHz,
CDCl3) δ 21.4, 21.7, 31.6, 42.4, 43.3, 46.3, 67.5, 127.8, 129.6, 129.8, 129.9,
135.5, 143.7, 206.4; IR (neat) cmꢀ1 2917s, 1726s, 1340 m, 1154s, 1105 m;
MS (ESI) m/e (% relative intensity) 329.1 (10) (M þ Na þ H)þ, 328.1
(55) (M þ Na)þ, 306.1 (100) (M þ H)þ; HRMS (ESI) m/e calcd for
C16H19NO3Sþ (M þ H)þ 306.1159, found 306.1147. Minor: Rf = 0.16
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Rf = 0.09 [1:4 EtOAc/hexanes]; white solid; mp = 126ꢀ128 °C; H
NMR (500 MHz, CDCl3) δ 0.89ꢀ0.97 (m, 3H), 1.00 (s, 18H), 2.40
(d, 1H, J = 17.0 Hz), 2.43 (s, 3H), 3.01 (dd, 1H, J = 6.5, 17.0 Hz), 3.40
(t, 1H, J = 10.5 Hz), 3.81 (dd, 1H, J = 7.5, 10.5 Hz), 3.83 (s, 1H), 4.19
(dd, 1H, J = 7.5, 9.5 Hz), 5.13 (d, 1H, J = 6.5 Hz), 6.10 (d, 1H, J = 6.0
Hz), 6.47 (dd, 1H, J = 1.5, 6.0 Hz), 7.33 (d, 2H, J = 8.0 Hz), 7.83 (d, 2H,
J = 8.5 Hz); 13C NMR (125 MHz, CDCl3) δ 12.3, 18.0, 18.1, 21.7, 44.4,
53.5, 69.2, 70.4, 77.3, 91.8, 127.9, 129.8, 131.0, 135.8, 138.0, 144.0,
201.4; IR (neat) cmꢀ1 2918s, 1724s, 1460 m, 1347s, 1116s; MS (ESI)
m/e (% relative intensity) 514.2 (20) (M þ Na)þ, 509.2 (100), 492.2
(75) (M þ H)þ; HRMS (ESI) m/e calcd for C25H37NO5SSiþ (M þ
H)þ 492.2235, found 492.2231.
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[1:3 EtOAc/hexanes]; colorless oil; H NMR (500 MHz, CDCl3) δ
1.63ꢀ1.70 (m, 2H), 2.08 (dt, 1H, J = 5.5, 11.5 Hz), 2.13ꢀ2.16 (m, 1H),
2.43 (s, 3H), 2.53ꢀ2.62 (m, 4H), 3.15 (ddd, 1H, J = 5.5, 6.0, 7.0 Hz), 3.73
(dd, 1H, J = 8.0, 10.5 Hz), 4.43 (d, 1H, J = 11.5Hz), 5.84 (ddd, 1H, J = 1.5,
3.0, 11.0 Hz), 6.02 (quintet of doublets, 1H, J = 2.5, 6.0 Hz), 7.31 (d, 2H,
J = 8.0 Hz), 7.88 (d, 2H, J = 8.5 Hz); 13C NMR (125 MHz, CDCl3)
δ 21.7, 23.9, 32.3, 40.7, 43.2, 48.3, 72.0, 127.9, 129.7, 131.0, 132.1, 136.9,
143.6, 205.8; IR (thin film) cmꢀ1 2849 m, 1723s, 1335 m, 1140s, 1098 m;
MS (ESI) m/e (% relative intensity) 328.1 (10) (M þ Na)þ, 306.1 (100)
(M þ H)þ; HRMS (ESI) m/e calcd for C16H19NO3Sþ (M þ H)þ
306.1159, found 306.1151.
Cycloadduct 69 (35 mg, 0.071 mmol) was obtained in 85% yield as a
4:1 mixture of diastereomers from allenamide (()-68 according to
the general procedure. Major: Rf = 0.24 [1:3 EtOAc/hexanes]; white
solid; mp = 73ꢀ74 °C; 1H NMR (500 MHz, CDCl3) δ 0.44 (qd, 6H,
J = 3.5, 7.5 Hz), 0.79 (t, 9H, J = 7.5 Hz), 2.39 (d, 1H, J = 15.5 Hz), 2.41
(s, 3H), 3.14 (dd, 1H, J = 5.0, 15.5 Hz), 3.32 (d, 1H, J = 11.5 Hz), 3.42 (s,
1H), 3.99 (dd, 1H, J = 4.0, 11.5 Hz), 4.12 (d, 1H, J = 3.5 Hz), 5.06 (d, 1H,
J = 5.5 Hz), 6.11 (d, 1H, J = 6.0 Hz), 6.34 (dd, 1H, J = 1.5, 6.0 Hz), 7.32
(d, 2H, J = 8.0 Hz), 7.79 (d, 2H, J = 8.5 Hz); 13C NMR (100 MHz,
CDCl3) δ 4.6, 6.7, 21.6, 44.4, 59.2, 68.3, 71.7, 78.7, 95.5, 128.1, 128.8,
129.6, 133.5, 136.7, 143.7, 200.9; IR (neat) cmꢀ1 2866 m, 1719s, 1415w,
1350s, 1166s; MS (ESI) m/e (% relative intensity) 473.2 (10) (M þ Na þ
H)þ, 467.2 (80), 450.2 (100) (M þ H)þ; HRMS (ESI) m/e calcd
for C22H31NO5SSiþ (M þ H)þ 450.1765, found 450.1750. Minor:
Cycloadduct 57 (25 mg, 0.065 mmol) was obtained in 80% yield as a
65:35 inseparable mixture of diastereomers from allenamide 56 according to
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the general procedure. Rf = 0.24 [1:1 EtOAc/hexanes]; colorless oil; H
NMR (500 MHz, CDCl3) Major δ 0.91 (s, 3H), 1.13 (s, 3H), 1.42 (td, 1H,
J = 4.0, 9.5 Hz), 1.67ꢀ1.75 (m, 1H), 1.93 (d, 1H, J = 18.0 Hz), 2.01ꢀ2.07
(m, 1H), 2.09 (t, 1H, J = 5.0 Hz), 2.11ꢀ2.15 (m, 1H), 2.28 (td, 1H, J = 8.5,
13.0 Hz), 2.36ꢀ2.42 (m, 1H), 2.41 (dd, 1H, J = 5.0, 17.5 Hz), 2.45ꢀ2.54
(m, 1H), 2.96 (dd, 1H, J = 7.5, 17.5 Hz), 3.17 (d, 1H, J = 15.0 Hz),
3.48ꢀ3.56 (m, 1H), 3.60 (s, 1H), 3.90 (d, 1H, J = 15.0 Hz), 4.10 (dd, 1H,
J = 8.5, 10.5 Hz), 4.26 (s, 1H), 5.05 (d, 1H, J = 7.5 Hz), 6.28 (d, 1H, J = 6.0
Hz), 6.48 (dd, 1H, J = 1.5, 6.0 Hz); Select resonances for minor δ 1.11 (s,
3H), 1.91 (d, 1H, J=18.0Hz), 2.99(dd, 1H, J= 7.0, 17.0 Hz), 4.03 (dd, 1H,
J= 8.5, 10.5 Hz), 4.22 (s, 1H), 6.27 (d, 1H, J= 6.5 Hz), 6.46 (dd, 1H, J=2.0,
6.5 Hz); 13C NMR (125 MHz, CDCl3) not obtained for inseparable
mixture; IR (thin film) cmꢀ1 2959 m, 1739s, 1415w, 1332s, 1144s; MS
(ESI) m/e (% relative intensity) 403.1 (10) (M þ Na þ H)þ, 402.2 (100)
(M þ Na)þ, 380.2 (10) (M þ H)þ; HRMS (ESI) m/e calcd for
C19H25NO5Sþ (M þ Na)þ 402.1346, found 402.1351.
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Rf = 0.12 [1:3 EtOAc/hexanes]; white solid; mp = 129ꢀ131 °C; H
NMR (500 MHz, CDCl3) δ 0.56 (q, 6H, J = 8.0 Hz), 0.90 (t, 9H,
J = 8.0 Hz), 2.40 (d, 1H, J = 17.0 Hz), 2.44 (s, 3H), 3.00 (dd, 1H, J = 6.5,
17.0 Hz), 3.38 (t, 1H, J = 10.5 Hz), 3.77 (dd, 1H, J = 7.5, 10.5 Hz),
3.85 (s, 1H), 4.07 (dd, 1H, J = 7.5, 9.5 Hz), 5.14 (d, 1H, J = 6.5 Hz), 6.08
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dx.doi.org/10.1021/jo200147h |J. Org. Chem. 2011, 76, 3246–3257