2. Theoretical Investigation of Double Bonds Effects on The oxy-Cope
Rearrangements and oxy-retro-ene Reactions
 

A. Ozgur Ozsar* and Nurettin Balcioglu
 

 Hacettepe University, Chemistry Department,  06810, Ankara, Turkey

Oxy-Cope rearrangements of 1,5-hexadien-3-ol, 1a, and its derivatives are  important reaction types in the organic chemistry to synthesize larger systems via ring enlargement. In this study, the double bond effects on the oxy-Cope rearrangements and the oxy-retro-ene reactions and the progress of reactions have been investigated using DFT method at the B3LYP/6-31G* level of theory. Additional double bond on C1-C2 bond of 1,5-hexadien-3-ol, 1a, decreases activation barrier by 2.8 kcal/mol for oxy-Cope type rearrangement. For oxy-retro-ene reactions, additional double bond on C1-C2 bond of 4-hydroxy-1-butene, 1c, has no significant effect on the activation enthalpy, but on C2-C3 bond, it was found that the activation barrier decreases 2.7 kcal/mol. Introducing the vinyl and the ethynyl groups on the 4-hydroxy-1-butene, 1c, 4-hydroxy-1-butyne, 2c, and 4-hydroxy-1,2-butadiene, 3c, at C-4 further decrease  activation enthalpy by about 1.9-4.0 kcal/mol for oxy-retro-ene reactions.

Keywords: DFT Studies, oxy-Cope rearrangement, oxy-retro-ene reaction, 1,5-hexadien-3-ol

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