Chemoenzymatic synthesis of chiral bipyridine ligands and their application in asymmetric oxidation, reduction and cyclopropanation reactions

ORGN 774

Tayeb Belhocine, belhocinet@hotmail.com, Derek R Boyd, dr.boyd@qub.ac.uk, Deirdre M. Murphy, D.Murphy@qub.ac.uk, Narain D Sharma, n.sharma@qub.ac.uk, and Christopher. C. R. Allen. School of Chemistry, Queen's University Belfast, David Keir building, Stranmillis road, BT9 5AG Belfast, United Kingdom
Recent work in our laboratory has shown that a new range of enantiopure cis-dihydrodiols, can be obtained from mono-and polycyclic- arenes and azaarenes by large-scale biotransformation methods, using selected bacterial mutant strains. containing different dioxygenase types. These cis-dihydrodiols can in turn be used in the synthesis of new enantiopure bipyridine and cis-amino-alcohol ligands.

Herein we report the biotransformation of 2-chloro-substituted -quinoline, -phenylpyridine and -biphenyl substrates to their corresponding cis-dihydrodiols and their use as precursors in the synthesis of enantiopure C2-symmetric bipyridine, bipyridine-N,N-dioxide and cis-amino-alcohol ligands.

These new chiral ligands have been tested in different asymmetric reactions including:-hydrogenation of ketones, allylic hydroxylation and cyclopropantion of alkenes. To date enantiomeric excess values in excess of 90% ee have been obtained in some cases.