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Mechanisms of ring contraction, C—H insertion and 1,2‐hydrogen migration of cyclobutylidene
Author(s) -
BingZe Wang,
CongHao Deng
Publication year - 1990
Publication title -
chinese journal of chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.28
H-Index - 41
eISSN - 1614-7065
pISSN - 1001-604X
DOI - 10.1002/cjoc.19900080203
Subject(s) - chemistry , cyclobutene , carbene , ab initio , hydrogen , contraction (grammar) , transition state , basis set , computational chemistry , ring (chemistry) , activation barrier , hydrogen bond , crystallography , stereochemistry , density functional theory , catalysis , molecule , organic chemistry , medicine
Isomerizations of cyclobutylidene 1 to methylenecyclopropane 2 , cyclobutene 3 and bicyclobutane 4 have been studied using ab initio method. Equilibrium and transition structures are fully optimized with 3–21G basis set. The reaction barriers are 78, 75 and 110 kJ/mol at 6–31 G ** , respectively, 1→2 occurs via the outward disrotation of two end C‐C bonds, 1→3 via the attack of an exo hydrogen to the carbene p AO before the transition state, and 1→4 is unable to compete with 1→2 and 1→3 for its higher barrier.