Massoud Motamed, Eric M. Bunnelle, Surendra W. Singaram, and Richmond Sarpong*
Department of Chemistry, University of California, Berkeley, California 94720
Department of Chemistry, University of California, Berkeley, California 94720
A neat reaction of aziridine, tethered to propargylic acetate, with PtCl2 catalyst as a way to access 1,2-dihydropyridines.
The reaction mechanism was proposed to be as shown below.
The authors explored this chemistry in continuation from their earlier work of a similar reaction with the epoxide derivative as shown.
The reactions were found to proceed well. Scope of the reaction was studied and illustrated in the table below.
Cases where the Ts group aziridine nitrogen was substituted with acyl group were also studied. In these cases although desired pyridine products were formed in good yields, byproducts of type 18 (as shown) were also formed.
This byproduct was formed by participation of acyl C=O group as proposed in the mechanism below.
As shown in Scheme 4, the dihydropyridine 5b could be used as a precursor to pyridine 20 demonstrating the utility of the products.
The reaction was also shown to be stereospecific, that is the stereochemistry in the starting material was effectively transferred to the product as shown in the scheme where stereochemistry of carbon bearing the phenyl group in 1a was retained in product 5a.
The reaction was also shown to be stereospecific, that is the stereochemistry in the starting material was effectively transferred to the product as shown in the scheme where stereochemistry of carbon bearing the phenyl group in 1a was retained in product 5a.
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