Maureen A. McLaughlin

Asymmetric routes to azasugars from chiral bicyclic lactams. Synthesis of 1,4-dideoxy-1,4-imino-D-lyxitol; L-deoxymannojirimycin; rhammo-1-deoxynojirimycin and 1-deoxy-6-epicastanospermine

Abstract By employing the appropriate chiral bicyclic lactams, the asymmetric total synthesis of four enantiopure azasugars mentioned in the title were successfully achieved. A series of diastereoselective oxidations ( OsO 4 NMO ) followed by diastereoselective reductions (BH3, 9-BBN) gave good yields of the trisubstituted (16) and tetrasubstituted (2,3,4) pyrrolidine and piperidines respectively.

A highly diastereoselective vinylogous Mannich condensation and 1,4-conjugate addition of (Z)-propenyl cuprate in the synthesis of an influenza neuraminidase inhibitor

A practical synthesis of neuraminidase influenza inhibitor, A-322278, has been developed. Asymmetry is introduced into the synthesis by an enzyme mediated ester hydrolysis. A highly diastereoselective vinylogous Mannich condensation reaction of N-Boc-2-tert-butyldimethylsilyloxypyrrole (TBSOP) and an N-(triphenylmethylsulfenyl)imine proceeds under thermodynamic control to assemble the framework. A significant temperature dependent rate difference for the transfer of (Z)- and (E)-propenyl moieties from a cuprate reagent during a 1,4-conjugate addition was observed. A very selective addition of cyanide to an N-acyliminium intermediate was employed to control the final stereocenter.

Preparation of endothelin antagonist ABT-627

An enantioselective synthesis of ABT-627 is described. The key transformation is a diastereoselective 6-endo-trig cyclization to produce a 3,4,5-trisubstituted-1,2-oxazine which is ring contracted to the 2,3,4-tri-substituted-pyrrolidine core of ABT-627.