2324
P. Castelani, J. V. Comasseto / Tetrahedron 61 (2005) 2319–2326
64.0, 31.8, 30.1, 22.2, 19.1, 13.7. LRMS m/z (rel. int.) 156
(MC, 6), 127 (12), 111 (45), 101 (19), 99 (44), 86 (16), 82
(12), 73 (45), 68 (30), 55 (100).
(d, JZ6.9 Hz, 3H), 0.85 (t, JZ7.4 Hz, 3H). 13C NMR
(125 MHz, CDCl3) d 168.1, 147.7, 120.9, 60.3, 33.5, 27.3,
25.3, 14.4, 13.5, 5.7. LRMS m/z (rel. int.) 170 (MC, 62), 155
(24), 127 (24), 125 (82), 124 (20), 113 (20), 109 (50), 97
(57), 96 (71), 95 (66), 83 (46), 82 (28), 81 (43), 69 (55), 67
(50), 55 (100), 53 (25). Anal. calcd for C10H18O2: C, 70.55,
H, 10.66; Found: C, 70.37, H, 10.68.
Z isomer [35066-42-3]. 1H NMR (300 MHz, CDCl3) d 6.21
(dt, JZ11.5, 7.5 Hz, 1H), 5.75 (dt, JZ11.5, 1.6 Hz, 1H),
4.16 (q, JZ7.1 Hz, 2H), 2.65 (dq, JZ7.5, 1.5 Hz, 2H),
1.47–1.33 (m, 4H), 1.28 (t, JZ7.2 Hz, 3H), 0.91 (t, JZ
7.5 Hz, 3H). 13C NMR (75 MHz, CDCl3) d 166.6; 150.4;
119.6; 63.7; 31.1; 30.7; 22.3; 19.2; 13.8. LRMS m/z (rel.
int.) 156 (MC, 20), 127 (48), 111 (31), 99 (100), 81 (24), 68
(26), 55 (63).
4.2.9. Ethyl (Z)-3,4,4-trimethyl-pent-2-enoate (15c).
(0.144 g, 85%) [21016-48-8]. IR nmax/cmK1 2972, 2873,
1724, 1623, 1457, 1444, 1372, 1245, 1179, 1055, 1027
1
(neat). H NMR (500 MHz, CDCl3) d 5.62 (q, JZ1.3 Hz,
1H), 4.14 (q, JZ7.1 Hz, 2H), 1.84 (d, JZ1.3 Hz, 3H), 1.28
(t, JZ7.1 Hz, 3H), 1.20 (s, 9H). 13C NMR (125 MHz,
CDCl3) d 168.0, 158.5, 116.6, 60.1, 36.4, 29.1, 24.0, 14.2.
LRMS m/z (rel. int.) 170 (MC, 2), 155 (72), 127 (51), 125
(63), 109 (53), 97 (99), 83 (31), 81 (47), 69 (31), 57 (36), 55
(100), 43 (41), 41 (76).
4.2.5. Ethyl (E)-4-methylhex-2-enoate (14b). (0.123 g,
79%) [78023-52-6]. IR nmax/cmK1 2965, 2932, 2877, 1721,
1653, 1461, 1369, 1308, 1269, 1243, 1186, 1159, 1136,
1
1042 (neat). H NMR (500 MHz, CDCl3) d 6.86 (dd, JZ
15.7, 7.8 Hz, 1H), 5.78 (dd, JZ15.7, 1.2 Hz, 1H), 4.18 (q,
JZ7.1 Hz, 2H), 2.24–2.19 (m, 1H), 1.40–1.34 (m, 2H), 1.29
(t, JZ7.1 Hz, 3H), 1.04 (d, JZ6.7 Hz, 3H), 0.88 (t, JZ
7.0 Hz, 3H). 13C NMR (125 MHz, CDCl3) d 167.0, 154.4,
119.8, 60.2, 38.2, 28.9, 19.2, 14.3, 11.6. LRMS m/z (rel. int.)
156 (MC, 10), 128 (10), 111 (37), 110 (29), 95 (34), 82 (40),
73 (26), 69 (28), 56 (27), 55 (100).
4.2.10. 4-Methyl-oct-3-en-2-one (16a). (0.097 g, 70%, 2:1
mixture (E:Z)). IR nmax/cmK1 2959, 2932, 2870, 1689,
1617, 1441, 1380, 1355, 1166, 961 (neat).
E isomer [23732-25-4]. 1H NMR (500 MHz, CDCl3) d 6.07
(s, 1H), 2.17 (s, 3H), 2.16–2.10 (m, 2H), 2.12 (d, JZ0.9 Hz,
3H), 1.47–1.30 (m, 4H), 0.88–0.86 (t, JZ6.8 Hz, 3H). 13C
NMR (75 MHz, CDCl3) d 198.2, 159.5, 124.0, 33.3, 32.4,
30.3, 25.3, 22.8, 13.4. LRMS m/z (rel. int.) 140 (MC, 2), 125
(2), 111 (4), 97 (9), 82 (4), 69 (8), 55 (46), 43 (100).
4.2.6. Ethyl (E)-4,4-dimethyl-pent-2-enoate (14c).
(0.132 g, 85%) [22147-62-2]. IR nmax/cmK1 2959, 2926,
1712, 1682, 1556, 1332, 1207, 1145, 1033 (neat). 1H NMR
(300 MHz, CDCl3) d 6.97 (d, JZ15.8 Hz, 1H), 5.73 (d, JZ
15.8 Hz, 1H), 4.19 (q, JZ7.1 Hz, 2H), 1.29 (t, JZ7.1 Hz,
3H), 1.08 (s, 9H). 13C NMR (75 MHz, CDCl3) d 167.3,
159.0, 116.7, 60.1, 33.7, 28.6, 14.3. LRMS m/z (rel. int.) 156
(MC, 16), 141 (51), 113 (42), 111 (57), 95 (41), 83 (100), 69
(29), 67 (52), 55 (78).
Z isomer [36219-17-7]. 1H NMR (500 MHz, CDCl3) d 6.05
(s, 1H), 2.58 (t, JZ7.3 Hz, 2H), 2.15 (s, 3H), 1.86 (d, JZ
1.1 Hz, 3H), 1.47–1.30 (m, 4H), 0.92 (t, JZ7.2 Hz, 3H). 13C
NMR (75 MHz, CDCl3) d 198.8, 158.9, 123.5, 40.9, 31.7,
29.7, 22.3, 19.2, 13.8. LRMS m/z (rel. int.) 140 (MC, 12),
125 (15), 111 (41), 83 (22), 69 (16), 55 (43), 43 (100).
4.2.7. Ethyl 3-methyl-hept-2-enoate (15a). (0.134 g, 79%,
10:1 mixture (Z:E)). IR nmax/cmK1 2963, 2932, 2867, 1716,
1648, 1453, 1378, 1241, 1193, 1149, 1042, 858 (neat).
4.2.11. 4,5-Dimethyl-hept-3-en-2-one (16b). (0.095 g,
68%, 5:1 mixture (E:Z)). IR nmax/cmK1 2965, 2931, 2876,
1687, 1615, 1459, 1377, 1356, 1216, 1174 (neat).
Z isomer [42778-40-5]. 1H NMR (500 MHz, CDCl3) d
5.65–5.64 (m, 1H), 4.13 (q, JZ7.1 Hz, 2H), 2.64–2.60 (m,
2H), 1.87 (d, JZ1.4 Hz, 3H), 1.47–1.42 (m, 2H), 1.40–1.34
(m, 2H), 1.27 (t, JZ7.1 Hz, 3H), 0.92 (t, JZ7.2 Hz, 3H).
13C NMR (125 MHz, CDCl3) d 166.4, 160.7, 116.0, 59.4,
33.2, 30.4, 25.2, 22.9, 14.3, 14.0. LRMS m/z (rel. int.) 170
(MC, 43), 141 (62), 128 (26), 125 (80), 113 (100), 100 (27),
96 (28), 95 (77), 82 (57), 69 (52), 67 (42), 56 (33), 55 (97).
1
E isomer [104664-46-2]. H NMR (500 MHz, CDCl3) d
5.99 (s, 1H), 2.08–1.98 (m, 1H), 2.11 (s, 3H), 1.98 (d, JZ
1.2 Hz, 3H), 1.34–1.26 (m, 2H), 0.97 (d, JZ6.8 Hz, 3H),
0.76 (t, JZ7.4 Hz, 3H). 13C NMR (75 MHz, CDCl3) d
199.2, 163.0, 123.3, 46.1, 32.1, 27.8, 19.1, 16.1, 12.2.
LRMS m/z (rel. int.) 140 (MC, 5), 125 (27), 112 (18), 97
(20), 83 (12), 69 (28), 67 (10), 55 (58), 43 (100).
E isomer [42778-90-5]. 1H NMR (500 MHz, CDCl3) d
5.66–5.65 (m, 1H), 4.14 (q, JZ7.1 Hz, 2H), 2.64–2.60 (m,
2H), 2.15 (d, JZ1.3 Hz, 3H), 1.47–1.42 (m, 2H), 1.40–1.34
(m, 2H), 1.28 (t, JZ7.1 Hz, 3H), 0.90 (t, JZ7.1 Hz, 3H).
13C NMR (125 MHz, CDCl3) d 167.0, 160.1, 115.5, 60.4,
40.7, 29.6, 22.3, 18.7, 14.3, 13.9. LRMS m/z (rel. int.) 170
(MC, 4), 128 (100), 125 (66), 113 (46), 100 (49), 95 (31), 83
(26), 82 (47), 69 (44), 67 (23), 56 (39), 55 (75).
1
Z isomer [104664-56-4]. H NMR (500 MHz, CDCl3) d
5.97 (s, 1H), 3.68 (sext, JZ7.2 Hz, 1H), 2.08 (s, 3H), 1.68
(d, JZ1.3 Hz, 3H), 1.34–1.26 (m, 2H), 0.92 (d, JZ6.8 Hz,
3H), 0.76 (t, JZ7.4 Hz, 3H). 13C NMR (75 MHz, CDCl3) d
198.7, 162.4, 125.1, 36.1, 32.2, 28.0, 19.4, 18.8, 11.8.
LRMS m/z (rel. int.) 140 (MC, 21), 125 (28), 111 (6), 97
(24), 83 (11), 69 (23), 67 (12), 55 (57), 43 (100).
4.2.8. Ethyl (Z)-3,4-dimethyl-hex-2-enoate (15b).
(0.138 g, 81%). IR nmax/cmK1 2962, 2929, 2869, 1715,
1642, 1455, 1378, 1222, 1154, 1039 (neat). 1H NMR
(500 MHz, CDCl3) d 5.64 (q, JZ1.2 Hz, 1H), 4.13 (q, JZ
7.1 Hz, 2H), 3.78 (sext, JZ7.1 Hz, 1H), 1.76 (d, JZ1.3 Hz,
3H), 1.39 (qn, JZ7.4 Hz, 2H), 1.27 (t, JZ7.1 Hz, 3H), 1.02
4.2.12. (E)-4,5,5-Trimethyl-hex-3-en-2-one (16c).
(0.091 g, 65%) [23732-21-0]. IR nmax/cmK1 2965, 2913,
2873, 1687, 1605, 1467, 1366, 1261, 1214, 1185. 1H NMR
(200 MHz, CDCl3) d 6.13 (s, 1H), 2.20 (s, 3H), 2.11 (d, JZ
1.1 Hz, 3H), 1.10 (s, 9H). 13C NMR (50 MHz, CDCl3) d
199.7, 165.6, 120.5, 37.8, 32.0, 28.5, 15.6. LRMS m/z (rel.