Gold(I)-catalyzed intramolecular [4 + 2] cycloaddition of ortho-(N-tethered 1,6-diynyl)benzaldehydes to 3,4-dihydrobenzo[f]isoquinolin-1(2H)-ones

Abstract

An efficient synthetic method to prepare 3,4-dihydrobenzo[f]isoquinolin-1(2H)-ones through gold(I)-catalyzed intramolecular [4 + 2] benzannulation of o-(N-tethered 1,6-diynyl)benzaldehydes at a low catalyst loading of 2 mol% is described. The product of 3,4-dihydrobenzo[f]isoquinolin-1(2H)-ones can be easily transformed to benzo[f]isoquinolin-1-ols by simply treating with phenylmagnesium bromide under mild conditions. The structures of compounds 2o and 2w were also ascertained by X-ray crystallographic analysis.