Tandem Wolff rearrangement-'tert-amino effect' sequence: Synthesis of 2-oxoindolinium enolate derivatives

Article abstract of DOI:10.1016/S0040-4020(97)00448-1

The thermolysis of 1-diazo-2-oxo-(2-N,N-disubstituted aminophenyl)ethylphosphonates 1 gave rise to 2-oxoindolinium enolate derivatives 4 through Wolff rearrangement and interaction of the tert-amino moiety with the ketene functionality. Variable amounts of either ammonium ylides 5 or of products resulting from their transformations were also formed during the course of the reaction. If the amino moiety was substituted by a benzyl or an allyl group, indolinones, resulting from [1,3] or [1,2] benzylic or allylic shifts, were isolated in place of compounds 4 and 5.