S. Metwally, M. Aly, M. Abd-Alla
Apr 12, 1991
Citations
0
Influential Citations
1
Citations
Journal
European Journal of Organic Chemistry
Abstract
4-(Dicyanomethylene)-3-methyl-1-phenyl-2-pyrazoline-5-one (1) readily reacts with α-amino acids and their esters by Michael addition and subsequent elimination of HCN to the adducts 2a–k. One of these, 2i (obtained from methyl glycinate), adds stereoselectively to N-phenylmaleimide with loss of the remaining cyano group. It is believed that the endo-transition state of lower energy leads to the major cycloadduct 5, whereas the exo-transition state gives 6 as the minor one.