Visible light-promoted radical benzannulation of diazoketones with alkynes leading to polysubsituted naphthols

A visible light-promoted radical benzannulation of diazoketones and alkynes for the synthesis of polysubsituted naphthols was developed. Unlike the classic Danheiser benzannulation of diazoketones and alkynes via vinylcarbene intermediates, the reaction proceeds through a radical process, affording various polysubsituted naphthols with different regioselectivity. It represents a rare example of the activation of diazoketones by visible light photoredox catalysis, which generates enolated vinyl radical ions under mild and environmentally friendly conditions. (C) 2017 Elsevier B.V. All rights reserved.