NISCAIR Online Periodicals Repository

NISCAIR ONLINE PERIODICALS REPOSITORY (NOPR)  >
NISCAIR PUBLICATIONS >
Research Journals >
Indian Journal of Chemistry -Section B (IJC-B) >
IJC-B Vol.51B [2012] >
IJC-B Vol.51B(08) [August 2012] >


Title: Effect of A1,3-strain on the stereochemistry of N-acetyl and N,O-diacetyl-r-2,c-6-diphenylpiperidin-4-one oximes
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 A1,3-strain by means of acetyl groups in r-2,c-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 N,O-diacetylpiperidin-4-one oximes 12-15 prefer to adopt twist-boat conformation with an equilibrium between syn and anti rotamers. From the variable temperature 1H NMR spectral studies carried out on N,O-diacetyl-t-3-methyl-r-2,c-6-diphenylpiperidin-4-one oxime 13, the syn-anti rotational barriers DG#AB and DG#BA have been found to be 44.2 and 43.5 kJ mol-1, respectively. The X-ray crystal structure of N,O-diacetyl-t-3-isopropyl-r-2,c-6-diphenylpiperidin-4-one oxime 14 also show twist-boat conformation. The conformational preferences obtained from the semiempirical MO calculations for N,O-diacetylpiperidin-4-one oximes 12-15 have been found to be similar to those predicted from the NMR spectral studies and X-ray crystallographic analysis. Similarly, the N-acetyl-r-2,c-6-diphenylpiperidin-4-one oximes 5-7 have been found to adopt twist-boat conformations.
Page(s): 1151-1162
CC License:  CC Attribution-Noncommercial-No Derivative Works 2.5 India
ISSN: 0975-0983(Online); 0376-4699(Print)
Source:IJC-B Vol.51B(08) [August 2012]

Files in This Item:

File Description SizeFormat
IJCB 51B(8) 1151-1162.pdf114.42 kBAdobe PDFView/Open
 Current Page Visits: 345 
Recommend this item

 

National Knowledge Resources Consortium |  NISCAIR Website |  Contact us |  Feedback

Disclaimer: NISCAIR assumes no responsibility for the statements and opinions advanced by contributors. The editorial staff in its work of examining papers received for publication is helped, in an honorary capacity, by many distinguished engineers and scientists.

CC License Except where otherwise noted, the Articles on this site are licensed under Creative Commons License: CC Attribution-Noncommercial-No Derivative Works 2.5 India

Copyright © 2012 The Council of Scientific and Industrial Research, New Delhi. All rights reserved.

Powered by DSpace Copyright © 2002-2007 MIT and Hewlett-Packard | Compliant to OAI-PMH V 2.0

Home Page Total Visits: 509459 since 06-Feb-2009  Last updated on 11-Apr-2014Webmaster: nopr@niscair.res.in