N-Iodosuccinimide-Promoted Cascade Trifunctionalization of Alkynoates: Access to 1,1-Diiodoalkenes

An efficient cascade trifunctioalization reaction of alkynoates with N-iodosuccinimide has been developed which proceeds through iodination, aryl migration, decarboxylation, and second iodination. This reaction represents an example of 1,1-difunctionalization of the acetylene bond and also provides a new strategy for the preparation of 1,1-diiodoalkenes.