bromoacetyl chloride and triethylamine in the presence of one equivalent of N- phenylmaleimide afforded cycloadducts 10 and 11 in 54% and 64% yield, respectively. These compounds are derived by dipolar cycloaddition of the mesoionic species 9 with the added dipolarophile. Cycloaddition of thioisomiinchnone 9 with an unsymmetrical dipolarophile such as phenyl vinyl sulfone afforded cycloadduct 12. The regiochemical ...
