The HSQC experiment shows correlations between protons and directly attached (one bond) heteratoms such as 13C or 15N. The HMBC (MB = multiple bond) experiment shows correlations between protons and heteroatoms that are based on small coupling constants. These typically occur for atoms 2, 3 or 4 bonds from each other.

The difference between the two amyrin isomers is in the position of 1 CH3 group.

Alpha has two methyls on separate carbons (19,20) and beta has two CH3's on 20.As all other CH3's are attached to quaternary carbons they will all appear as singlets. Alpha amyrin is easy to distinguish as the two CH3's on 19 and 20 will appear as doublets in a 1H NMR due to the coupling with the adjacent CH. Beta has the two CH3 on 20 also as singlets.

Thanks prof Clemens. Kindly give more insight on the position Alpha and beta, also need more light on lupoel and lupenone and information on their H nmr

Hello AA

HSQC is an NMR experiment that gives communication between a 1H resonance with a carbon resonance for H and C that are attached respectively. So this is H-C single bond correlation whereas HMBC is correlation for 1H resonance and 13C resonance that are either 2, 3 or 4 bonds away. Gradient HMBC experiment will filter the correlations to mainly 3 bonds away.

Lupeol - Lupane type triterpenoid with OH group at C-3 and a terminal double bond characteristic to lupines whereas lupenone has a ketogenic group at C-3 position. Lupenone is an oxidised lupeol. Alpha and Beta are generic terms and are relatively used.

Thanks