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Dimethyl 1,3-Acetonedicarboxylate
3169
acetate:hexane 4:96, 30 g of silica gel) affording methyl-4-carbomethoxy-
4-alkyl-3-methoxy-2-butenoate IVa–f.
E-Methyl- 4- carbomethoxy- 4-methyl-3- methoxy-2- butenoate IVa.
.
Yield: 78%. IR (neat) 1147, 1630, 1711, 1744 cmÀ1 1H NMR ꢀ ppm
1.35 (d, 3H, J ¼ 7.1 Hz), 3.66 (s, 3H), 3.68 (s, 3H), 3.69 (s, 3H), 4.96 (q,
1H, J ¼ 7.1 Hz), 5.10 (s, 1H). 13C NMR ꢀ ppm 14.25, 40.95, 50.96, 52.07,
55.90, 91.26, 167.58, 172.40, 172.95. MS (EI) m/z (relative intensity) 202
(Mþ, 22), 170 (84), 142 (100), 127 (40), 111 (51). Anal. calcd. for
C9H14O2: C, 53.46; H, 6.93. Found: C, 53.66; H, 6.90.
E-Methyl-4-carbomethoxy-4-isopropyl-3-methoxy-2-butenoate IVb.
Yield: 79.7%. m.p. 40–41ꢁC. IR (KBr) 1153, 1198, 1633, 1709, 1739,
2956 cmÀ1
.
1H NMR ꢀ ppm 0.86 (d, 3H, J ¼ 6.9 Hz), 1.02 (d, 3H,
J ¼ 6.9 Hz), 2.25–2.45 (m, 1H), 3.66 (s, 3H), 3.68 (s, 3H), 3.70 (s, 3H),
4.79 (d, 1H, J ¼ 9.6 Hz), 5.17 (s, 1H). 13C NMR ꢀ ppm 19.60, 21.25, 28.12,
50.94, 51.87, 52.31, 55.75, 93.05, 167.62, 170.80, 171.37. MS (EI) m/z
(relative intensity) 230 (Mþ, 16), 198 (55), 183 (74), 128 (100). Anal.
calcd. for C11H17O5: C, 57.64; H, 7.42. Found: C, 57.72; H, 7.45.
E-Methyl-4-carbomethoxy-4-allyl-3-methoxy-2-butenoate IVc. Yield:
80%. IR (neat) 1146, 1630, 1711, 1743, 2952 cmÀ1 1H NMR ꢀ ppm
.
2.40–2.56 (m, 1H), 2.64–2.76 (m, 1H), 3.64 (s, 3H), 3.68 (s, 3H), 3.69
(s, 3H), 4.96–5.10 (m, 3H), 5.16 (s, 1H), 5.68–5.83 (m, 1H). 13C NMR
ꢀ ppm 33.26, 45.81, 50.95, 52.06, 55.78, 92.68, 116.68, 134.88, 167.52,
170.87, 171.27. MS (EI) m/z (relative intensity) 228 (Mþ, 24), 213 (85),
197 (89), 164 (59), 137 (89), 109 (100). Anal. calcd. for C11H16O5: C,
57.89; H, 7.01. Found: C, 58.02; H, 6.94.
E-Methyl-4-carbomethoxy-4-hexyl-3-methoxy-2-butenoate IVd. Yield:
1
76%. IR (neat) 1146, 1197, 1631, 1715,1744, 2859 cmÀ1. H NMR ꢀ ppm
0.88 (t, 3H, J ¼ 6.9 Hz), 1.15–1.35 (m, 8H), 1.65–2.05 (m, 2H), 3.65 (s, 3H),
3.67 (s, 3H), 3.69 (s, 3H), 4.93 (dd, 1H, J ¼ 6.38 Hz, and J ¼ 6.26 Hz).
13C NMR ꢀ ppm 14.01, 22.54, 29.01, 31.57, 31.58, 46.03, 50.97, 52.02,
55.83, 90.92, 92.44, 167.64, 171.73, 171.98. MS (EI) m/z (relative intensity)
272 (Mþ, 13), 169 (100), 156 (98), 128 (68), 241 (48). Anal. calcd. for
C14H24O5: C, 61.69; H, 8.81. Found: C, 61.71; H, 8.79.
E-Methyl-4-carbomethoxy-4-benzyl-3-methoxy-2-butenoate IVe.
Yield: 85.2%. IR (neat) 1144, 1437, 1630, 1710, 1742, 2951 cmÀ1
.
1H NMR ꢀ ppm 2.99 (dd, 1H, Jgem ¼ 13.8 Hz, Jxa ¼ 7.2 Hz, Hx), 3.28 (dd,
1H, Jgem ¼ 13.8 Hz, Jba ¼ 7.5 Hz, Hb), 3.60 (s, 3H), 3.62 (s, 3H), 3.66 (s,
3H), 5.03 (s, 1H), 5.30 and 5.31 (dd, 1H, Jax ¼ 7.2, Jab ¼ 7.5 Hz, Ha), 7.22
(bs, 5H). 13C NMR ꢀ ppm 35.22, 47.59, 50.92, 52.13, 55.76, 92.79, 126.21,
128.06, 129.05, 138.53, 167.33, 170.56, 171.20. MS (EI) m/z (relative
intensity) 278 (Mþ, 32), 246 (50), 219 (34), 187 (71), 91 (100). Anal.
calcd. for C15H18O5: C, 6.74; H, 6.47. Found: C, 64.82; H, 6.50.