Nakyen Choy

Linear free energy relationships in the Bergman cyclization of 4-substituted-1,2-diethynylbenzenes

Abstract A series of 4-substituted-1,2-diethylnylbenzenes were prepared ( 1a – f ) and subjected to Bergman cyclization. Bulk cyclization proceeded to produce the corresponding 2-substituted naphthalenes ( 2a – f ) in good yields (59–78%). Kinetic experiments show a linear free energy relationship between the cyclization rate and the Hammett σ m substituent coefficient and the Swain–Lupton field and resonance parameters.

Synthesis of irreversible HIV-1 protease inhibitors containing sulfonamide and sulfone as amide bond isosteres

Abstract Novel irreversible HIV-1 protease inhibitors containing sulfonamide and sulfone as amide bond isosteres were designed, synthesized, and kinetically characterized. A representative compound 2 displayed rapid, time-dependent inactivation of HIV-1 protease and high potency in cell culture with IC50 of 6.6 nM.

Synthesis and redox properties of novel alkynyl flavins

Abstract The synthesis of C7 and/or C8 alkynyl flavins is described. The yields range from 14–48% over six steps. The reduction potentials of these compounds are in good agreement with the values expected based on the Hammett substituent coefficients.

NMR and topochemical studies of peptidomimetic HIV-I protease inhibitors containing a cis-epoxide amide isostere

NMR and topochemical studies of irreversible HIV-1 protease inhibitors containing a cis-epoxide as amide isostere have been carried out to identify conformational preference of the inhibitors in solution. The inhibitors prefer to adopt extended conformations similar to the beta-strand in solution.

β-Methanesulfonyl-L-valine as a novel, unnatural amino acid surrogate for P2 in the design of HIV protease inhibitors.

Abstract β-Methanesulfonyl-L-valine as a surrogate for asparagine and valine was designed, synthesized, and characterized. A representative compound 1 showed IC50 of 4.9 nM.

An efficient and enantioselective synthesis of a chiral primary amine

Abstract An efficient and enantioselective method for the preparation of a chiral primary amine has been developed. Starting from N-protected L or D-amino acid the sequence involves coupling with N-methoxy-N-methylamine, acylation, olefination with potassium bis(trimethylsilyl)amide, and hydrogenation.