Site-specific preparation of 2-carboalkoxy-4-substituted naphthalenes and 9-alkylphenanthrenes and evidence for an allene intermediate in the novel base-catalyzed cyclization of 2-alkynylbiphenyls.

[Structure: see text] A site-specific preparation of 2-carboalkoxy-4-substituted naphthalenes and 9-alkylphenanthrenes is described. The successful cyclization of an allene intermediate provides supportive evidence for the previously proposed mechanism.