SYNTHESIS OF EXOCYCLIC ENAMIDES
1759
dd, J ¼ 17.0 Hz, J ¼ 11.0 Hz, ¼ CH), 5.42 (1H, dd, J ¼ 17.0 Hz, J ¼ 1.0 Hz,
¼ CH2), 5.17 (1H, dd, J ¼ 11.0 Hz, J ¼ 1.0 Hz, ¼ CH2), 4.35 (2H, s, NCH2),
2.70–1.90 (4H, m); 13C NMR (CDCl3) d 175.7 (s), 139.2 (d), 138.2 (s), 128.4
(d), 128.3 (d), 127.1 (d), 116.6 (t), 91.3 (s), 43.0 (t), 34.3 (t), 29.1 (t); m/z (EI):
217 (M+, 22%), 199 (89%), 170 (60%), 146 (11%), 106 (62%), 91 (100%),
84 (42%), 65 (62%); HRMS, M+ found 217.1102, C13H15NO2 requires
217.1103.
5-Hydroxy-1-[2-(tetrahydropyran-2-yloxy)ethyl]-5-vinylpyrrolidin-2-one
(1c). To a solution of 1-[2-(tetrahydropyran-2-yloxy)ethyl]pyrrolidine-
2,5-dione (2.0 g, 8.80 mmol) in THF (70 ml), cooled to ꢁ78ꢀC, was added
vinylmagnesium bromide (13.2 ml, 13.2 mmol, 1M solution in THF) drop-
wise. When the addition was complete the mixture was stirred at 20ꢀC for
4 h. It was then poured onto saturated ammonium chloride (30 ml), the
layers separated and the aqueous layer extracted with diethyl ether
(2ꢂ20 ml). The combined organic extracts were dried (MgSO4) and evapo-
rated to give an orange oil which was purified by column chromatography
(70:30 ethyl acetate: 40–60ꢀC petroleum ether) to give 1c as a colourless oil
1
(1.24 g, 55%), IR, ꢀmax (thin film): 3330, 1680 cmꢁ1; H NMR (CDCl3) d
5.82 (1H, m, ¼ CH), 5.64–5.50 (1H, m, ¼ CH2), 5.44–5.30 (1H, m, ¼ CH2),
4.64 (1H, m, OCHO), 4.00–3.35 (6H, m), 3.20–3.04 (1H, m), 2.80–2.55 (1H,
m), 2.45–2.25 (1H, m), 2.20–1.30 (7H, m); 13C NMR (CDCl3) d 176.7 (s),
176.6 (s), 139.9 (d), 117.5 (t), 117.3 (t), 98.9 (d), 98.8 (d), 90.1 (s), 65.6 (t),
65.2 (t), 62.5 (t), 62.3 (t), 40.1 (t), 39.7 (t), 34.0 (t), 33.8 (t), 30.1 (t), 29.3 (t),
25.2 (t), 25.0 (t), 19.4 (t), 19.2 (t); m/z (FAB): 278 (MNa+, 32%), 256 (20%),
238 (70%), 172 (32%), 154 (100%), 111 (28%); HRMS, MNa+ found
278.1380, C13H21NO4Na requires 278.1368.
5-(2-Hydroxyethylidene)-1-methylpyrrolidin-2-one (3a). To a solution
of 5-hydroxy-1-methyl-5-vinylpyrrolidin-2-one13 (0.20 g, 1.42 mmol) in etha-
nol free dichloromethane (10 ml) was added pyridinium para-toluenesulfo-
nate (36 mg, 0.14 mmol). The mixture was then stirred at 20ꢀC for 2 h,
diluted with diethyl ether, washed with half-saturated brine and the organic
layer dried (MgSO4) and evaporated to give an oil which was purified
by column chromatography (90:10 ethyl acetate: 40–60ꢀC petroleum
ether) to give 3a as a colourless oil (142 mg, 71%); IR, ꢀmax (thin
film): 3380, 1690 cmꢁ1
;
1H NMR (CDCl3) d 4.84 (1H, tt, J ¼ 7.5 Hz,
J ¼ 2.0 Hz, ¼ CH2) 3.98 (2H, d, J ¼ 7.5 Hz, CH2OH), 2.88 (3H, s, CH3),
2.70 (2H, m, CH2CO), 2.45 (2H, m, ¼ CCH2); 13C NMR (CDCl3) d 175.8
(s), 145.8 (s), 96.4 (d), 65.5 (t), 28.6 (t), 26.6 (q), 21.2 (t); m/z (EI) 141 (M+,
48%), 124 (100%), 119 (13%), 114 (47%), 98 (42%), 88 (33%), 84 (69%),
68 (59%), 57 (79%); HRMS, M+ found 141.0783, C7H11NO2 requires
141.0790.