Syntheses of isochromenes and naphthalenes by electrophilic cyclization of acetylenic arenecarboxaldehydes

Highly substituted 1H-isochromenes, isobenzofurans and pyranopyridines are prepared by allowing o-(1-alkynyl)arenecarboxaldehydes and ketones to react with I2, ICl, NIS, Br2, NBS, p-O2NC6H4SCl or PhSeBr and different alcohols or carbon-based nucleophiles at room temperature. Naphthyl ketones and iodides can be prepared by the reaction of 2-(1-alkynyl)arenecarboxaldehydes with I2 and simple olefins or alkynes.