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New Insights on the Mechanism of Thermal Cleavage of Unsaturated Bicyclic Diaziridines: A DFT Study
Author(s) -
Arshadi S.,
Bekhradnia A. R.,
Ahmadi S.,
Karami A. R.,
Pourbeyram S.
Publication year - 2011
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.201180253
Subject(s) - chemistry , bicyclic molecule , delocalized electron , steric effects , bond cleavage , computational chemistry , stereochemistry , organic chemistry , catalysis
A DFT calculations are carried out at UB3LYP/6‐311++G (3df, 2p) levels of theory to study electrocyclic thermal cleavage of four ( R ) derivatives of unsaturated bicyclic diaziridines, 1 X‐ R , to produce corresponding ( Z ) and ( E ) azomethine imides ( 2 X‐ Z , 2 X‐ E , 3 X‐ Z and 3 X‐ E ), where X=H, Me, t ‐Bu and Ph. Cleavage of 1 X‐ R series to form the most stable 3 X‐ Z product, (path 2) is found the favored procedure because of delocalized negative charge on five atoms and lower steric effect in related transition state. According to IRC calculations in paths 1 and 2, C 6 N 1 bond is cleaved before the rate determinating step (transition state). The stability of unsaturated bicyclic diaziridines and their corresponding ( Z ) and ( E ) azomethine imides is in the following order in gas phase and chloroform, tetrahydrofuran, and acetone solvents: 3 X‐ Z < 3 X‐ E < 2 X‐ Z < 2 X‐ E < 1 X‐ R < 1 X‐ S .