2-Dimensional NMR in Carbohydrate Structural Analysis

Abstract

2-Dimensional FT NMR techniques have greatly expanded the power of NMR to unravel complex chemical structures. Homonuclear 2D J-resolved experiments can be helpful in sorting out complex over lapping coupling patterns, while homonuclear chemical shift correla tion experiments can be used to determine the homonuclear coupling networks. Heteronuclear chemical shift correlation experiments can indicate the source of direct or long-range heteronuclear couplings, and hence can be used to relate the proton spectrum to the carbon spectrum. Carbon-carbon connectivity experiments reflect carbon homonuclear couplings, and, while the most insensitive of all the techniques, can be the most powerful in directly revealing the molecular framework. Techniques such as these can be used either individually or in combination to reveal part or all of the structural features of both simple and complex carbohydrates. The general features of 2D experiments are discussed in the context of their application to carbohydrates.