Comparative Structural Studies of [3.1.0]-Fused 2’,3’-Modified 8-D-Nucleosides by X-ray Crystallography, NMR Spectroscopy, and Molecular Mechanics Calculations

Positions of the phenyl hydrogens were held fixed during refmement. Isotropic thermal parameters for the methyl hydrogens were set a t 1.2 times the initial equivalent isotropic thermal parameter of the methyl carbon and were not refined. Remaining hydrogen isotropic thermal parameters were refined. An extinction correction was applied. The absolute configuration was confirmed in the refinement. The value of 7 was 1.3 (3) with 7 = +1 indicating the proper absolute configuration and 7 = -1 the wrong choice. Structure solution details are included in the supplementary material. Standard atomic scattering factors were used.” Computer programs used are contained in the program package SHELXTL.29