2''-SUBSTITUTED ALKALOIDS OF THE CINCHONA SERIES, ESPECIALLY 2''-SUBSTITUTED QUININE, QUINIDINE, CINCHONIE, CINCHONIDINE AND DIHYDRO ANALOGS OF FORMULAS I AND II, AND THEIR SALTS, ARE PREPARED BY TREATING AR-N-OXIDES OF THE ALKALOIDS WITH THE CORRESPONDING ORGANOMETALLIC REAGENT AND, IF DESIRED, CONVERTING THE FREE BASES THUS FORMED INTO PHARMACEUTICALLY-ACCEPTABLE ACID-ADDITION SALTS. THE NEW COMPOUNDS ARE PHARMACOLOGICALLY ACTIVE, ESPECIALLY ANTIMALARIALLY AND ANTI-ARRHYTHMICALLY.