β-Fluoroamphetamines via the Stereoselective Synthesis of Benzylic Fluorides
摘要:
A range of substituted aryl epoxides undergo efficient ring-opening hydrofluorination upon treatment with 0.33 equiv of BF3 center dot OEt2 in CH2Cl2 at -20 degrees C to give the corresponding syn-fluorohydrins, consistent with a mechanism involving a stereoselective S(N)1-type epoxide ring-opening process. The benzylic fluoride products of these reactions are valuable templates for further elaboration, as demonstrated by the preparation of a range of aryl-substituted beta-fluoroamphetamines.