491024-87-4Relevant academic research and scientific papers
Dynamic helical chirality of an intramolecularly hydrogen-bonded bisoxazoline
Preston, Adam J.,Fraenkel, Gideon,Chow, Albert,Gallucci, Judith C.,Parquette, Jon R.
, p. 22 - 26 (2007/10/03)
The synthesis and conformational properties of 2,6-bis-[2-((4S)-4-methyl-4,5-dihydro-1,3-oxazol-2- yl)phenyl]carbam oylpyridines, 2, have been described. Bisoxazoline 2a was prepared in five steps from 2-nitrobenzoyl chloride in an overall yield of 71%. In contrast to related structures such as 1, bisoxazoline 2a exhibits a highly biased P-type helical conformation in solution and in the solid state. In the crystal lattice, 2a further assembles into a left-handed helical superstructure aligned along the crystallographic c axis. The barrier to helical interconversion, as measured by line-shape analysis of the temperature-dependent 1H NMR spectra of thiobenzyl derivative 2b, was determined to be quite low (ΔG? = 12.3 kcal/mol), indicating the presence of a highly dynamic helical chirality.
