The gradient-enhanced 1H,29Si HMQC experiment was applied to tetra-TMS-α-O-methyl-D-glucopyranose and tetra-TES-α-O-methyl-D-glucopyranose as test samples. All the expected 2J(1H, 29Si) and 3J (1H,29Si) cross peaks were observed, allowing the full 29Si 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.
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Provera et al. (2001) studied this question.