ASSIGNMENTS OF THE H-1 AND C-13 NMR-SPECTRA OF PSEUDOSYMMETRIC HETEROCYCLES USING THE HMQC-TOCSY EXPERIMENT TO DIFFERENTIATE OVERLAPPING SPIN SYSTEMS

The H-1 nmr spectra of phenanthro[9',10':4,5]thieno[2,3-c]quinoline, benzo[f]phenanthro[9',10':4,5]thieno[2,3-c]quinoline and benzo[h]phenanthro[9',10':4,5]thieno[2,3-c]quinoline are highly congested. For each compound, all protons abide in an aromatic environment complicated by pseudo-symmetric regions which result in multiple overlap of the different spin systems these molecules contain. We illustrate here the utility of the HMQC-TOCSY experiment to identify spin systems when the proton spectrum is highly congested. To complete the assignment of the H-1 and C-13 nmr spectra of each compound the HMBC experiment is used to assign the quaternary carbons.