Comparison of13C Resolution and Sensitivity of HSQC and HMQC Sequences and Application of HSQC-Based Sequences to the Total1H and13C Spectral Assignment of Clionasterol

Abstract

It is demonstrated that HSQC gives considerably better 13C resolution and sensitivity than HMQC for CH2 groups of natural products, particularly when combined with linear prediction. Similarly, coupled HSQC spectra provide a useful method for the determination of 1H multiplet structure and consequent assignment of individual CH2 protons as axial or equatorial in fused cyclohexane rings. These and related techniques are used to assign 1H and 13C spectra of the marine sterol clionasterol. © 1997 John Wiley & Sons, Ltd.