Reactions of tosylhydrazones of benzaldehyde and benzophenone with cyanoalkenes in a basic two-phase system

Reaction of tosylhydrazones 1a,b with cyanoalkenes 3a,b, carried out in the presence of concentrated aq. sodium hydroxide in dioxane, afforded either cyanocyclopropanes 5, 9 or pyrazoles 13, 14 and 16, 17. The process takes p lace via generation of diazocompounds 2a,b from la,b their [3+2] cycloaddit ion to 3a,b with the formation of unstable pyrazolines 4, further fate of w hich depends on the structure of R-1 and R-2 substituents. (C) 2001 Elsevie r Science Ltd. All rights reserved.