Abstract: HMQC-TOCSY experiment is a useful 2D NMR technique for elucidating structures of organic molecules that possess independent spin systems. From HMQC-TOCSY spectrum, we can obtain information of all the proton connectivities in the F₂ dimension and information of the carbon connectivity in the F₁ dimension for a given spin system, so the chemical shifts of both proton and carbon can be simultaneously assigned. In this paper, two examples, annosquamosin A, which is a cyclopeptide, and prostratoside A, which is a triterpenoidal saponin, are given to demonstrate the application of this technique to the natural products.

Key words: HMQC-TOCSY, Annosquamosin A, Prostratoside A