New Insights on the Mechanism of Thermal Cleavage of Unsaturated Bicyclic Diaziridines: A DFT Study |
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| Authors: | S Arshadi A R Bekhradnia S Ahmadi A R Karami S Pourbeyram |
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| Institution: | 1. Department of Chemistry, Payame Noor University, Tehran, Iran;2. Pharmaceutical Sciences Research Center, Department of Medicinal Chemistry, Mazandaran University of Medical Sciences, Sari, Iran;3. Shahid Rajaee Teacher Training University, Tehran, Iran |
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| Abstract: | 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, 1X‐R , to produce corresponding (Z) and (E) azomethine imides ( 2X‐Z , 2X‐E , 3X‐Z and 3X‐E ), where X=H, Me, t‐Bu and Ph. Cleavage of 1X‐R series to form the most stable 3X‐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, C6? N1 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: 3X‐Z < 3X‐E < 2X‐Z < 2X‐E < 1X‐R < 1X‐S . |
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| Keywords: | unsaturated bicyclic diaziridines azomethine imides electrocyclic thermal cleavage conrotatory motion molecular modeling conformational analysis |
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