【摘 要】
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A computational study using M06 method on the cyclopropanation of endo-dicyclopentadiene with Simmons-Smith zinc carbenoids is reported.Each channel proceeds via the methylene-transfer mechanism.The c
【机 构】
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Key Laboratory for Green Chemical and Technology,School of Chemical Engineering and Technology,Tianj
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A computational study using M06 method on the cyclopropanation of endo-dicyclopentadiene with Simmons-Smith zinc carbenoids is reported.Each channel proceeds via the methylene-transfer mechanism.The channels with IZnCH2I attacking the double bonds from the exo-face have much lower barrier(about 16.17-18.43 kcal/mol)in gas phase,compared with the channels from the endo-face(21.80-31.13 kcal/mol).So P1 and P3 are the primary cyclopropanated compounds,and P5 is the sole final product,representing remarkable stereospecificity.Considering the bulk solvent effect of diethyl ether,the barriers are decreased about 0.50-7.77 kcal/mol.The solvated(ICH2)2Zn can further reduce the barriers about 0.18-2.30 kcal/mol and retain the stereospecificity.Our computational results suggest that both IZnCH2I and(ICH2)2Zn might be the active species in real reaction system,in good agreement with experimental observations.As regard to the solvent effect,the polar continuum model is more realistic than the direct involvment of diethyl ether molecules.
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