Nucleophile-dependent mode-selective cyclization reactions initiated by hydrogen bonding-directed 1,6/1,4-addition.

Tandem cyclization initiated by hydrogen bonding-directed 1,6/1,4-addition of nucleophiles onto 1,3-diynyl ketones is described. The reaction with alcohols and thiols preferentially generates formal enyne ring-closing metathesis (RCM) products, whereas amines favor 5-exo-dig carbocyclization to generate indanone derivatives.