Boat conformations. Analysis and simulation of the complex H-1 NMR spectrum of methyl 2,6 : 3,4-dianhydro-alpha-D-altropyranoside

The complex H-1 NMR spectrum of methyl 2,6:3,4-dianhydro-alpha-D-altropyran oside (1) has been analyzed and simulated in detail by using input paramete rs derived from experimental H-1 chemical shifts, long- and short-range cou pling constants, spin-lattice relaxation times, and effective, spin-spin re laxation times obtained by trial and error matching of the experimental and simulated spectra. The C-13 spin-lattice relaxation times of 1 have also b een measured, and along with the H-1-H-1 long- and short-range coupling con stants, have been interpreted in terms of the geometry of 1 defined by mole cular dynamics with simulated annealing. (C) 2000 Elsevier Science Ltd. All rights reserved.