Please use this identifier to cite or link to this item: http://nopr.niscair.res.in/handle/123456789/14513
Title: <span style="font-size:12.0pt;font-family: "Times New Roman";mso-fareast-font-family:"Times New Roman";mso-ansi-language: EN-GB;mso-fareast-language:EN-US;mso-bidi-language:AR-SA" lang="EN-GB">Effect of A<sup>1,3</sup>-strain on the stereochemistry of <i style="mso-bidi-font-style:normal">N</i>-acetyl and <i style="mso-bidi-font-style:normal">N</i>,<i style="mso-bidi-font-style:normal">O</i>-diacetyl-<i style="mso-bidi-font-style:normal">r</i>-2,<i style="mso-bidi-font-style:normal">c</i>-6-diphenylpiperidin-4-one oximes</span>
Authors: Vijayalakshmi, R
Muthukumar, M
Ponnuswamy, S
Jeyaraman, R
Keywords: A1,3-strain
N-acetylpiperidin-4-one oximes
N,O-diacetylpiperidin-4-one oximes
NMR spectra
Semiempirical MO calculation
X-ray crystal structure
Variable temperature 1H NMR spectra
Issue Date: Aug-2012
Publisher: NISCAIR-CSIR, India
Abstract: The stereochemical consequences of the introduction of A<sup>1,3</sup>-strain by means of acetyl groups in <i style="mso-bidi-font-style:normal">r</i>-2,<i style="mso-bidi-font-style:normal">c</i>-6-diphenylpiperidin-4-one oximes have been studied using various NMR spectral techniques, X-ray crystallographic analysis and semiempirical MO calculations. The NMR spectral results show that the <i style="mso-bidi-font-style:normal">N</i>,<i style="mso-bidi-font-style: normal">O</i>-diacetylpiperidin-4-one oximes <b style="mso-bidi-font-weight: normal">12-15</b> prefer to adopt twist-boat conformation with an equilibrium between <i style="mso-bidi-font-style:normal">syn</i> and <i style="mso-bidi-font-style: normal">anti</i> rotamers. From the variable temperature <sup>1</sup>H NMR spectral studies carried out on <i style="mso-bidi-font-style:normal">N</i>,<i style="mso-bidi-font-style:normal">O</i>-diacetyl-<i style="mso-bidi-font-style: normal">t</i>-3-methyl-<i style="mso-bidi-font-style:normal">r</i>-2,<i style="mso-bidi-font-style:normal">c</i>-6-diphenylpiperidin-4-one oxime <b style="mso-bidi-font-weight:normal">13</b>, the <i style="mso-bidi-font-style: normal">syn</i>-<i style="mso-bidi-font-style:normal">anti</i> rotational barriers <span style="font-family:Symbol;mso-ascii-font-family: " times="" new="" roman";mso-hansi-font-family:"times="" roman";mso-char-type:symbol;="" mso-symbol-font-family:symbol"="" lang="EN-GB">DG<sup>#</sup><sub>AB</sub> and <span style="font-family:Symbol;mso-ascii-font-family:" times="" new="" roman";="" mso-hansi-font-family:"times="" roman";mso-char-type:symbol;mso-symbol-font-family:="" symbol"="" lang="EN-GB">DG<sup>#</sup><sub>BA</sub> have been found to be 44.2 and 43.5 kJ mol<sup>-1</sup>, respectively. The X-ray crystal structure of <i style="mso-bidi-font-style:normal">N</i>,<i style="mso-bidi-font-style:normal">O</i>-diacetyl-<i style="mso-bidi-font-style:normal">t</i>-3-isopropyl-<i style="mso-bidi-font-style: normal">r</i>-2,<i style="mso-bidi-font-style:normal">c</i>-6-diphenylpiperidin-4-one oxime <b style="mso-bidi-font-weight:normal">14</b> also show twist-boat conformation. The conformational preferences obtained from the semiempirical MO calculations for <i style="mso-bidi-font-style:normal">N</i>,<i style="mso-bidi-font-style:normal">O</i>-diacetylpiperidin-4-one oximes <b style="mso-bidi-font-weight:normal">12-15 </b>have been found to be similar to those predicted from the NMR spectral studies and X-ray crystallographic analysis. Similarly, the <i style="mso-bidi-font-style:normal">N</i>-acetyl-<i style="mso-bidi-font-style:normal">r</i>-2,<i style="mso-bidi-font-style:normal">c</i>-6-diphenylpiperidin-4-one oximes <b style="mso-bidi-font-weight:normal">5-7</b> have been found to adopt twist-boat conformations. </span></span>
Description: 1151-1162
URI: http://hdl.handle.net/123456789/14513
ISSN: 0975-0983(Online); 0376-4699(Print)
Appears in Collections:IJC-B Vol.51B(08) [August 2012]

Files in This Item:
File Description SizeFormat 
IJCB 51B(8) 1151-1162.pdf114.42 kBAdobe PDFView/Open


Items in NOPR are protected by copyright, with all rights reserved, unless otherwise indicated.