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DOI: 10.1055/sos-SD-036-00032

Cox, L. R.Science of Synthesis, (200836111.

The formation of primary alkanols from oxiranes (and larger cyclic ethers) requires regioselective ring opening at the more hindered end of a terminal oxirane. The selectivity and ease with which this occurs is heavily dependent on the substituents on the oxirane, the reagents, and the reaction conditions. Generally, if the ring-opening mechanism involves the build-up of appreciable positive charge in the transition state, then cleavage of the more substituted CO bond is more likely. Such regioselective opening can be further encouraged through judicious choice of substituents on the oxirane; thus aryl groups and alkenes favor ring opening at the more substituted terminus. Other substituents, such as carbonyl groups in α,β-epoxy ketones, and related systems, can also control the regioselectivity of the ring opening to favor the formation of primary alkanols.

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