Acetals of lactams and amides. 60. N- and O-alkylation of 5-oxo-5,6,7,8-tetrahydrocarbostyryils. Synthesis of isoxazolo[5,4-f]- and pyrazolo[3,4-f]quinolines

The alkylation of 5-oxo-5,6,7,8-tetrahydrocarbostyrils has been examined by GLC. It has been found that, irrespective of the reaction conditions and the alkylating agent used, both N- and O-alkylation occur. When triethyloxonium fluoroborate and N,N-DMF diethyl acetal are used O-alkylation predominates, and with alkyl halides, N-alkylation. Reaction of N-ethyl-5-oxo-5,6,7,8-tetrahydrocarbostyril and 2-ethoxy-5-oxo-5,6,7,8-tetrahydrotetrahydroquinoline with DMF diethyl acetal gives the 6-dimethylaminomethylene derivatives, treatment of which with hydrazine hydrate or hydroxylamine affording isoxazolo[5,4-f]- or pyrazolo[3,4-f]quinolines.