The preparation of quinine, quinidine, isomers and derivatives thereof from the correspondingly substituted 4-methylquinoline and 1-acyl(or 1-H)-3-vinyl(or lower alkyl)-4-piperidine acetic acid esters (or acetaldehyde) through alternative series of reaction steps which comprise, condensation, halogenation, deacylation, reduction, cyclization and hydroxylation, is described. Also described is the preparation of 1-acyl(or 1-H)-3vinyl-4-piperidineacetic acids and esters thereof and 1-acyl-3vinyl-4-piperidineacetaldehyde utilizing the corresponding 7acyldecahydro-2H-pyrido(3,4-d)azepin-2-one, prepared from 2-acyl1,3,4,7,8,8a-hexahydro-6(2H)-isoquinolone. The end products are useful as antimalarial and antiarrhythmic agents.