Regiochemical control of the ring opening of aziridines by means of chelating processes .2. Synthesis and ring-opening reactions of aziridines derived from 5,6-dihydro-2H-pyran and of the diastereoisomeric cis- and trans-aziridines derived from 3-(benzyloxy)cyclohexene, 2-(benzyloxy)3,6-dihydro-, and 2-(benzyloxy)-6-methyl-3,6-dihydro-2H-pyran

The regiochemical outcome of the ring opening of the activated and unactivated title aziridines was examined, in some cases a nice degree of regiocontrol can be obtained depending on the opening reaction conditions (standard, metal-assisted, or under acid-proton catalysis). The results have been rationalized by admitting the incursion, under appropriate reaction conditions, of chelated bidentate structures in which the metal or, in some cases, the proton is coordinated between the aziridine nitrogen and the O-heterofunctionality. (C) 1997, Elsevier Science Ltd.