Process for producing eburnane derivatives

摘要

A compound of the formula: <IMAGE> (I) wherein R1 is a C1-C6 alkyl group and R is a hydrogen atom or a C1-C6 alkyl group, and their salts, which are useful as cerebral vasodilator; and a compound of the formula: <IMAGE> (II) wherein R2 is a hydrogen atom or a C1-C6 alkyl group, R3 is a hydrogen atom or the formula: -CO2R1 (R1 is a C1-C6 alkyl group) and W is an oxygen atom, an imino group or <IMAGE> but not an imino group in case that R3 is a hydrogen atom, which are intermediates of the compound (I), useful per se as cerebral vasodilator and/or antihypertensive agents.