A cascade reaction of indoles with propargylic diols
involving an unprecedented metal-free 1,2-indole migration onto an
alkyne is here described. DFT calculations support a mechanism
consisting in a concerted nucleophilic attack of the indole nucleus
with loss of water followed by the 1,2-migration and subsequent
Nazarov cyclization. This Brønsted acid-catalyzed protocol affords
indole-functionalized benzofulvene derivatives in high yields.
