ENHANCED HYDROGEN-BONDING OF WATER TO DIELS-ALDER TRANSITION-STATES - AB-INITIO EVIDENCE

被引:132
作者
BLAKE, JF
LIM, D
JORGENSEN, WL
机构
[1] PFIZER INC, DIV CENT RES, GROTON, CT 06340 USA
[2] YALE UNIV, DEPT CHEM, NEW HAVEN, CT 06511 USA
关键词
D O I
10.1021/jo00083a021
中图分类号
O62 [有机化学];
学科分类号
070303 ; 081704 ;
摘要
Ab initio molecular orbital calculations reveal enhanced hydrogen bonding of a water molecule to the transition states for the Diels-Alder reactions of cyclopentadiene with methyl vinyl ketone (MVK) and acrylonitrile. The optimal interaction energies are found to be 1.5-2.0 kcal/mol more favorable for hydrogen bonding to the oxygen or nitrogen in the transition states than for the dienophiles. This supports the assertion from a prior simulation study that the observed rate accelerations for Diels-Alder reactions in aqueous solution arise from this hydrogen-bonding effect in addition to a relatively constant hydrophobic term.
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页码:803 / 805
页数:3
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