engleski

A computational study of regioselectivity in ß- lactam iminothiazolidinone formation

Density functional theory calculations were performed to explain the different regioselectivity for the formation of β-lactam iminothiazolidinones. Computational results were in agreement with experimental observations that phenyl and cyclohexyl derivatives led to the thermodynamically more stable regioisomers formed by cyclization at the nitrogen atom directly attached to the β- lactam ring which was in contrast to the n- hexyl derivative where the regioisomer with the β-lactam ring attached to the imino bond is instead more stable. It was demonstrated that the different regioselectivity was the consequence of larger steric effects when bulky substituents and the leaving ethoxy group were in close contact during the cyclization step.

iminothiazolidinones regioselectivity ; DFT calculations ; free energy barrier ; steric effects

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