THE USE OF HMQC-TOCSY EXPERIMENTS FOR ELUCIDATING THE STRUCTURES OF BICYCLIC LACTAMS - UNCOVERING A SURPRISE REARRANGEMENT IN THE SYNTHESIS OF A KEY PRO-PHE BUILDING-BLOCK

HMQC-TOCSY experiments were used to unequivocally assign the ring skeletons of several bicyclic lactams. This work demonstrated the power of these techniques for establishing the complete carbon connectivity of peptide building blocks with closely overlapping protons. In addition, it has led to the discovery of a surprise rearrangement reaction and allowed for the correction of a previously misassigned Pro-Phe building block ring skeleton.