Synthesis and Catalytic Ability of Diazaphospholenes

Abstract

This thesis presents a facile entry into diazaphospholene catalysis, harnessing pre- catalysts formed through the reaction of diazaphospholene-bromide compounds with neopentyl alcohol, to afford crystalline pre-catalysts. Their application in the hydroboration of imines and 1,4-reductions gives novel insight into their reactivity, as these heterocycles had yet to be employed in these catalyzed reactions. Mechanistic insights into the role of the catalyst, as well as potential decomposition pathways were explored. Next, enantioenriched diazaphospholene pre-catalysts were developed. These chiral pre-catalysts were applied in the asymmetric hydroboration of imines, to afford amines with enantiomeric ratios of up to 88:12. The monoamine oxidase inhibitor drug Rasagiline (employed in the treatment for Parkinson’s disease) was synthesized through these methods affording high selectivity and is the first asymmetric synthesis of this drug. Finally, efforts towards the use of diazaphospheniums as Lewis acids in the splitting of dihydrogen, and hydrogenation of imines are described.