Long-range two-dimensional1H-29Si heteronuclear shift correlation using gradients. Application to tetra-TMS-?-O-methyl-D-glucopyranose and tetra-TES-?-O-methyl-D-glucopyranose

The gradient-enhanced H-1,Si-29 HMQC experiment was applied to tetra-TMS-alpha -O-methyl-D-glucopyranose and tetra-TES-alpha -O-methyl-D-glucopyranose as test samples. All the expected (2)J(H-1, Si-29) and (3)J(H-1, Si-29) cross peaks were observed, allowing the full Si-29 NMR assignment. An analysis of the trend of 29Si chemical shifts depending on the position of the silylating group in the sugar ring and on the different hindrances of TMS and TES groups is also reported. Copyright (C) 2001 John Wiley & Sons, Ltd.