room temperature under reduced pressure. The unreacted dimethyl fumarate was removed by filtration and the residue placed under vacuum for 12 h to remove the unreacted enamine, leaving 0.46 g of 3b as yellow oil. Attempts to further purify 3b resulted in isomerization to 3a: NMR (CDC13) 0.92 (s, 3 ), 1.30 (s, 3 H), 2.7-3.2 (m, 8 H), 3.58 (s, 6 H); IR (thin film) 1737 cm"1 11.Acknowledgment. Support of this work by the National Science Foundation (CHE 78-01120) is gratefully acknowledged.