A method for stabilizing the cis prolyl peptide bond: influence of an unusual n¡ú¦Ð<sup>?sup> interaction in 1,3-oxazine and 1,3-thiazine containing peptidomimetics
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- 作者：Damodara N. Reddy ; Ravula Thirupathi ; Shama Tumminakatti ; Erode N. Prabhakaran
- 关键词：n&rarr ; ¦Ð&lowast ; Interactions ; Oxazine ; Thiazine ; cis&ndash ; trans Isomerism ; cis Peptide bond
- 刊名：Tetrahedron Letters
- 出版年：2012
- 出版时间：15 August, 2012
- 年：2012
- 卷：53
- 期：33
- 页码：4413-4417
- 全文大小：647 K
文摘
The cis/trans isomer ratios of the Xaa-Pyr (Pyr = pyrrolidine) 3¡ã amide bonds are significantly high (¡«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¡ú¦Ð<sub>i?1sub><sup>?sup> interaction, selectively stabilizes the cis conformer and the n)(n repulsion destabilizes the trans conformer of these molecules. Both these electronic effects oppose the steric effects in the 3¡ã amide bond. The structural requirements for manifestation of these electronic effects are determined.