Model route to 5-bromo-3,4-dihydro-4- hydroxy-7,9,10-trimethoxy-1,3-dimethyl-1H- naphtho[2,3-c]pyran: A potential precursor to extended quinines

Abstract

A protocol has been developed for the synthesis of the linear naphthopyran 16, by the TiCl4-catalyzed isomerization of 2,5-dimethyl dioxolane 1, having a methoxy group at position 1′ and a bromine atom at position 4′ of the naphthyl precursor to favor isomerization at position 2′.