Regiochemical Control of the Ring Opening of 1,2-Epoxides by Means of Chelating Processes. 4. Synthesis and Reactions of the cis- and trans-Oxides Derived from 3-cyclohexene

Article abstract of DOI:10.1021/jo00032a022

The synthesis and nucleophilic addition reactions of diastereoisomeric title epoxides cis-7 and trans-8 were studied.While the ring-opening reactions of trans epoxide 8 are rationalized by means of steric, stereoelectronic, and conformational arguments, the analogous reactions of cis epoxide 7 indicate the ability of this isomer to react through chelated intermediates when metal salt catalyst is used.In 7 chelation reaction conditions led to a significant increase of nucleophilic attack on the C-1 oxirane carbon; the lack of reversal of the regiochemistry of the ring opening on passing from nonchelating to chelating reaction conditions suggests that cis epoxide 7 reacts through its more stable conformation in both of the two different operating conditions.