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

Arunkumar Natarajan, V. Ramamurthy

Research output: Contribution to journalArticle

21 Scopus citations

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.

Original languageEnglish (US)
Pages (from-to)4533-4542
Number of pages10
JournalOrganic and Biomolecular Chemistry
Volume4
Issue number24
DOIs
StatePublished - Dec 7 2006

ASJC Scopus subject areas

  • Biochemistry
  • Physical and Theoretical Chemistry
  • Organic Chemistry

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