New synthesis of 1-[(3,4-dimethoxyphenyl)methoxymethyl]-6,7-dimethoxyisoquinoline (setigerine), a naturally occurring alkaloid, and some derivatives of papaverine

A novel and improved synthetic route for the preparation of the new alkaloid setigerine, isolated from Papaver setigerum DC, and some new 3,4-dihydropapaverine and papaverine derivatives is reported. This method is based on the side chain chlorination of 1-benzyl-3,4-dihydroisoquinolines using N-chlorosuccinimide (NCS) and subsequent reaction with sodium methoxide in methanol to give the corresponding isoquinolines.