Asymmetric induction during photocyclization of chiral and achiral α-oxoamides within achiral zeolites

Natarajan, Arunkumar ; Ramamurthy, V. (2006) Asymmetric induction during photocyclization of chiral and achiral α-oxoamides within achiral zeolites Organic and Biomolecular Chemistry, 4 (24). pp. 4533-4542. ISSN 1477-0520

Full text not available from this repository.

Official URL: http://pubs.rsc.org/en/Content/ArticleLanding/2006...

Related URL: http://dx.doi.org/10.1039/B611387G, Paper

Abstract

The photochemistry of 31 α-oxoamides capable of undergoing ?γ-hydrogen transfer has been examined within zeolites. These molecules, upon excitation, yield two products-a β-lactam and oxazolidinone-in solution, both resulting from γ-hydrogen transfer. While in benzene the major product is oxazolidinone, within an MY zeolite, the main product is a β-lactam. In this investigation, we have focused our attention on asymmetric induction in the formation of the β-lactam product. Two approaches-using a chiral inductor and chiral auxiliary-have been employed. While in solution, in the presence of chiral inductors, achiral α-oxoamides yield β-lactams with zero enantioselectivity; within zeolites, an ee of up to 44% has been achieved. α-Oxoamides appended with a chiral auxiliary gave β-lactams with less than 5% diastereoselectivity in solution while within zeolites, the same α-oxoamides gave the products with de's of up to 83%. Such a remarkable influence of zeolites is attributed to an alkali ion interaction with the reactant α-oxoamides and to the confined environment of the zeolite interior. At this stage, we have not been able to provide a model with predictive power and further work is needed to understand this valuable asymmetric induction strategy.

Item Type:Article
Source:Copyright of this article belongs to Royal Society of Chemistry.
ID Code:55905
Deposited On:19 Aug 2011 07:48
Last Modified:19 Aug 2011 07:48

Repository Staff Only: item control page