Application of organolithium and related reagents in synthesis. Part 21.1 Synthetic strategies based on ortho-aromatic metallation. A concise regiospecific synthesis of arylnaphthalanes as precursors of naphthylisoquinoline alkaloids

Abstract

A novel procedure is described for synthesising regioselectively substituted biaryls such as 12. It involves converting phthalides 4, via cycloaddition of dimethyl acetylenedicarboxylate to 1-arylisobenzofurans 6, into dimethyl 1-arylnaphthalene-2,3-dicarboxylates 8, which upon hydrolytic decarboxylation give lactones 11 and then esters 12.