Regiochemical Control of the Ring Opening of 1,2-Epoxides by Means of Chelating Processes. 7. Synthesis and Ring-Opening Reactions of cis- and trans-Oxides Derived from 2-(Benzyloxy)-3,6-dihydro-2H-pyran

Article abstract of DOI:10.1021/jo00094a025

The regiochemical outcome of the ring opening of 1,2-epoxides bearing polar remote functionalities through chelation processes assisted by metal ions was verified in a conformationally semirigid cyclic oxirane system in which the polar functionality is both directly inserted into the cyclic system and present on the cyclic system itself.Diastereoisomeric cis 4 and trans epoxide 5, derived from 2-(benzyloxy)-3,6-dihydro-2H-pyran, were prepared and some of their opening reactions (azidolysis, aminolysis, Cl(-) addition, and LiAlH4 reduction) were studied.The regioselectivity observed is largely dependent for both 4 and 5 on the opening (standard or metal-assisted) reaction conditions, and a regioalternating process is almost obtained.