Synthesis, Fourier transform infrared, 1D and 2D NMR spectral studies on the conformation of two new cholesteryl 4-alkoxyphenyl-40 benzoates

Two new cholesteryl 4-alkoxyphenyl-40-benzoates (CnH2nþ1OC6H4C6H4COOCh), where Ch represents cholesteryl moiety and n ¼ 10 and 16) have been synthesized and their molecular orientation at ambient temperature were studied. The structure determination on these compounds was performed in solid state by infrared spectroscopy based on vibrational analysis wherein the cholesteryl–phenyl and phenyl– aliphatic carbon linkages were concluded. Their molecular structures were further ascertained through the 1H and 13C NMR spectra along with two-dimensional COSY, NOESY, ROESY, 1H–13C HMQC and HMBC. The long-range connectivity as concluded from the NOESY, ROESY and HMBC spectra together with the related data led to a postulation that the title compounds in the liquid state exist in the conformation whereby the cholesteryl moiety was not lying along the entire molecular long axis. The cholesteryl fragment was presumed to be bent at the ester linkage of OyC–O and the phenyl rings located between cholesteryl and alkoxy chain group are not coplanar. q 2003 Elsevier B.V. All rights reserved