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A method for stabilizing the cis prolyl peptide bond: influence of an unusual n -> pi* interaction in 1,3-oxazine and 1,3-thiazine containing peptidomimetics

Reddy, Damodara N and Thirupathi, Ravula and Tumminakatti, Shama and Prabhakaran, Erode N (2012) A method for stabilizing the cis prolyl peptide bond: influence of an unusual n -> pi* interaction in 1,3-oxazine and 1,3-thiazine containing peptidomimetics. In: TETRAHEDRON LETTERS, 53 (33). pp. 4413-4417.

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Official URL: http://dx.doi.org/10.1016/j.tetlet.2012.06.031

Abstract

The cis/trans isomer ratios of the Xaa-Pyr (Pyr = pyrrolidine) 3 degrees amide bonds are significantly high (similar to 90% cis) in the novel peptidomimetics where Pyr contains 1,3-oxazine (Oxa) or 1,3-thiazine (Thi) at its 2 position. We find that an unusual n -> pi(i-1)* interaction, selectively stabilizes the cis conformer and the n X n repulsion destabilizes the trans conformer of these molecules. Both these electronic effects oppose the steric effects in the 3 degrees amide bond. The structural requirements for manifestation of these electronic effects are determined. (c) 2012 Elsevier Ltd. All rights reserved.

Item Type: Journal Article
Additional Information: Copyright for this article belongs to PERGAMON-ELSEVIER SCIENCE LTD.
Keywords: n -> pi* Interactions;Oxazine;Thiazine;cis-trans Isomerism;cis Peptide bond
Department/Centre: Division of Chemical Sciences > Organic Chemistry
Division of Chemical Sciences > Solid State & Structural Chemistry Unit
Date Deposited: 27 Nov 2012 10:56
Last Modified: 27 Nov 2012 10:56
URI: http://eprints.iisc.ernet.in/id/eprint/45087

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