GB982071A - Process for the production of emetine and related compounds - Google Patents

Abstract

The invention comprises the preparation of compounds of the general formula <FORM:0982071/C2/1> (wherein R represents a hydrocarbon group and wherein one or more substituents, especially alkoxy or methylenedioxy groups, may be present in the 31, 41, 51, 61, 71 81, 8, 9, 10 and/or 11 positions) by oxidation of corresponding compounds in which the nitrogen atom of the isoquinoline nucleus carries a substituent of the formula <FORM:0982071/C2/2> (wherein R1 represents a hydrocarbon group) by means of an alkali metal alkoxide and a ketone stable in the presence of alkali, and the combination of this process with the preparation of the starting materials by reduction of a compound of the general formula <FORM:0982071/C2/3> (optionally substituted as before) by means of a metal/ammonia or metal/amine reducing system to a compound of the general formula <FORM:0982071/C2/4> which, after isomerization at the 3-position under strong enolizing conditions, is reduced with a metal/acid reducing system or with hydrazine and alkali or by conversion to a thioketal and reduction of this with hydrazine and alkali or with a Raney metal, preferably in the presence of hydrogen. (Under suitable conditions, isomerization and the second reduction can be effected simultaneously). When the starting material contains methoxy groups (e.g. in the preparation of emetine or isoemetine), these may undergo hydrolysis during the oxidation process, in which event the resulting hydroxy groups may be re-methylated. Specification 977,788 is referred to.