Base-catalysed elimination of hydrogen chloride from the chlorohydrin of a Reissert compound: novel interconversion of isoquinoline and isochromene ring systems

Abstract

The Reissert compound, 2-benzoyl-1-cyano-1,2-dihydroisoquinoline (1), forms a chlorohydrin (2; R = H) which, when treated with base, eliminates hydrogen chloride to give, depending upon conditions, the rearranged heterocycles, 1-benzoylamino-1-cyanoisochromene (3), 1-benzoyliminoisochromene (4), 1-ethoxy-3-phenylisoquinoline (5; R = H), and 1-ethoxy-4-formyl-3-phenylisoquinoline (5; R = CHO).