FREQUENTIOSELECTIVITY AND REGIOSELECTIVITY IN-PHASE TRANSFER CATALYSIS - SOME OBSERVATIONS ON CONTROL BY CATALYST STRUCTURE

Selective mono- or bis-benzylation, 'frequentioselectivity', of diisop ropyl ketone (1) is achieved by choice of the right phase transfer cat alyst while the N/N'-methylation of 4-nitroimidazole (7) can also be i nfluenced to a certain extent by the nature of the catalyst; in both c ases benzo-15-crown-5 stands out in its potential for selectivity cont rol.