Aufklärung der 1H- und 13C-NMR-spektren sowie der kristallstruktur ungesättigter glycosylphosphonate und konformationsberechnungen an modellen

Abstract

By application of a modified LAOCN-3 program a complete elucidation of the 1H NMR spectra of 2,3-unsaturated glycosyl phosphonates 1–5 could be achieved. The exactly determined nJ(H, H) and novel nJ(C, P) coupling constants are discussed, and permit a conclusive deduction of the conformations. The 13C NMR spectra of 1 to 6 can be fully interpreted. By a close inspection of chemical shifts as well as 1J(C-H) and nJ(C, P) coupling constants the conformational assignment is supported. For all the derivatives the correlations 1J(C-1,H e)> 1J(C-1, H a) and 1J(C-1, P e) > 1J(C-1, P a) can be used for the assignment of anomers. The crystal structure of 1 is in accordance with this assignment of anomers and displays an unexpected conformation. Calculations by MINDO-3 in resembling model compounds serve to elucidate such conformative effects.