Heteroatom effect on potential energy topology. A novel reaction mechanism of stereospecific Staudinger synthesis

The Staudinger synthesis of various β-carbolines and thienopyridines with acetyl chloride derivatives led to novel β-lactam-type fused heterocyclic compounds. The reaction was stereospecific, giving exclusively the cis cycloadducts as racemates. The enthalpy profile and the driving force for the cis-selectivity of this cycloaddition was studied by high level quantum chemical calculations and was assigned to a new effect of the neighbouring heteroatom of the acyl group. In the course of the reaction a new side product was formed supporting the mechanistic results.

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