The Synthesis of 13-Spiro-substituted Protoberberines via the Tandem Addition - Cyclisation Reaction of 3-Methoxyphthalide Anions to 3,4-Dihydroisoquinolines

All articles of this category The reaction of the anion of 3-methoxyphthalide with 3,4-dihydroisoquinolines affords 13-spiro-substituted protoberberines rather than the expected 8,13-dioxo derivatives. Whilst the parent 3,4-dihydroisoquinoline reacts stereospecifically to yield the (13S*,13aS*) diastereomer, the 1-methyl derivative affords exclusively the (13R*,13aS*) isomer. This change in stereochemical outcome is attributed to conformational changes induced by the methyl group in the putative 8,13-dioxo-intermediates. anion addition - phthalides - 3,4-dihydroisoquinolines - protoberberines