Reverse turn induced π-facial selectivity during polyaniline-supported cobalt(II) salen catalyzed aerobic epoxidation of N-cinnamoyl L-proline derived peptides

Nandy, Jyoti Prokosh ; Prabhakaran, E. N. ; Kiran Kumar, S. ; Kunwar, A. C. ; Iqbal, Javed (2003) Reverse turn induced π-facial selectivity during polyaniline-supported cobalt(II) salen catalyzed aerobic epoxidation of N-cinnamoyl L-proline derived peptides Journal of Organic Chemistry, 68 (5). pp. 1679-1692. ISSN 0022-3263

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Official URL: http://pubs.acs.org/doi/abs/10.1021/jo020352j

Related URL: http://dx.doi.org/10.1021/jo020352j

Abstract

A novel chemo- and diastereoselective aerobic epoxidation of the N-cinnamoyl peptides catalyzed by polyaniline-supported cobalt(II) salen (PASCOS) is described. The N-cinnamoyl proline derived peptides 1 show a high π-facial selectivity during these epoxidations. The origin of this diastereoselectivity in 1 has been attributed to (i) the propensity of the N-cinnamoyl proline amide to exist predominantly as trans rotamer in CDCl3, DMSO-d6, and CH3CN medium and (ii) existence of these peptides as organized structures (γ- and β-turns) due to the presence of intramolecular hydrogen bonds. An extensive solution NMR and MD simulation study on 1d and 1f indicates that the origin of the high π-facial selectivity is due to the well-defined γ- and β-turns which result in the hindrance of one face of the cinnamoyl double bond in the transition state of the epoxidation reaction.

Item Type:Article
Source:Copyright of this article belongs to American Chemical Society.
ID Code:16971
Deposited On:16 Nov 2010 13:13
Last Modified:17 Feb 2011 04:51

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