Enantioselective ring-contraction reactions have not been widely reported. We have developed an enantioselective ring contraction of 5,6-dihydro-2-benzo[][1,4]oxazocines, affording enantiomerically enriched 3,4-dihydro-2-1,4-benzoxazine derivatives as single regioisomers. An acidic additive is necessary in order to obtain the products with good yields and enantiomeric ratios (up to 93% yield, 98:2 er). The reaction was successfully performed on a gram scale, and the products can be derivatized easily.
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