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[摘要]:Enantiomerically pure 2-(p-tolylsulfinyl)benzylcopper reagents react with propargyl bromides and mesylates, affording enantiomerically pure allenes with central and axial chirality. Both regioselectivity (S(N)2' processes) and configuration at the chiral axis are completely controlled by the sulfinyl group. The stereoselectivity at the benzylic position is very high. Complete kinetic resolution and moderate dynamic resolution of racemic propargylic mesylates can be achieved. This stereochemical behavior can be explained by assuming the stabilization of the benzylcopper by the sulfinyl oxygen and the association of the triple bond to the metal as a previous step of the intramolecular S(N)2' nucleophilic attack. |
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