SIMPLE PROCESS FOR PREPARING 6-SUBSTITUTED 7-OXO-PGI DOWN 1 DERIVATIVES

The present invention relates to a process for the preparation of compounds of the general Formula I (I) (wherein A is a straight or branched chain alkylene group having 1-5 carbon atoms; B is ethylene, Z or E vinylene, or ethynylene; R1 stands for hydrogen, an alkyl group having 1-5 carbon atoms or a pharmaceutically acceptable cation; R2 is hydrogen, an alkanoyl group having 1-5 carbon atoms or aroyl; R3 is hydrogen or methyl; R4 is a straight or branched chain alkyl group having 1-8 carbon atoms or an optionally monosubstituted aryloxymethyl group; R5 stands for hydrogen or an alkyl group having 1-5 carbon atoms) which comprises oxidizing a compound of the Formula III, IV or V (III) (IV) or (V) or a mixture thereof R6 is hydrogen or an alkyl or alkanoyl group having 1-5 carbon atoms with a mild electrophilic oxidizing agent and if desired reacting the compound of the Formula I thus obtained wherein R5 is hydrogen with an alkanol containing 1-5 carbon atoms in the presence of boron trifluoride etherate in a manner known per se to yield the corresponding compound of the Formula I in which R5 is an alkyl group having 1-5 carbon atoms.