Diethyl Cyclopropylidenemalonate:Facile Preparation,Generation in situ,and Various Transformations

摘要

Reductive cyclopropanation of triethyl methanetricarboxyl-ate(4a)with ethylmagnesium bromide in the presence of titanium tetraisopropoxide furnished diethyl 2-(l'-hydroxycy-clopropyljmalonate(5a)in 50%yield.Dehydromesylation of the mesylate of cyclopropanol 5a,generated in situ,by treatment with an excess of triethylamine gave diethyl Cyclopropylidenemalonate 3-Et as a highly reactive,unstable compound,which could be isolated as an oil in 39%yield,but more favorably could also be generated in situ from the mesylate or the acetate 11(prepared from 5a in 90%yield)and trapped without isolation with various N-,O-,S-,and C-nu-cleophiles.Thus,ammonia,dimethylamine,isopropylamine,