Analgesic benzomorphans prepn - with little or no addictive propertie

摘要

Benzomorphans of formula (I): (where R1 and R2 are 1-3C alkyl; R3-R5 are H or 1-3C alkyl and R6 is H, OH, 1-3C alkyl or 1-3C alkoxy) and their salts are obtained in good yield and purity by reacting a pyridine of formula (VI) with a halide of formula (VII) (where X is halogen), reacting the resulting quaternary salt of formula (IV) with a Grignard reagent of formula (V) (where Y is halogen), reducing the resulting dihydro cpd. (III) to the tetrahydro cpd. (II): and cyclising (II) or a salt thereof on a 0.2-2.0:1 w/w mixture of P2O5 and H3PO4.