P.M.R. SPECTRA AND CONFORMATION OF ACRYCLIC CARBOHYDRATES . ISOMERIC 3,4,5,6-TETRA-ACETOXY-TRANS-1-NITRO-1-HEXENES

The vicinal coupling constants derived from the p.m.r. spectra of the title compounds are consistent with the planar, zigzag conformation of the carbon skeleton (C-2-C-6) for the d-Pitarabino isomer but not for the d-xylo and d-ribo isomers. The latter possess an unfavourable, non-bonded interaction between acetoxyl groups on alternate carbon atoms in the zigzag conformation. Some of the p.m.r. spectra provide examples of deceptively simple ABX type systems. © 1969.