Da-Ming Du

Synthesis of novel chiral polyamide macrocycles containing pyridyl side-arms and their molecular recognition properties

Abstract Seven novel C 2 -symmetrical macrocycles containing pyridyl units have been prepared by the cyclic condensation of homochiral diamide intermediates with 2,6-pyridinedicarbonyl dichloride under high dilution at room temperature. The molecular recognition of these homochiral macrocycles for amino acid derivatives has been characterized by various spectroscopic methods such as IR, FAB-MS, fluorescence and UV–vis. The macrocycle 11 exhibited significant chiral recognition towards the enantiomers of d - and l -alanine methyl ester hydrochlorides for which association constants have been determined. Molecular modeling was also used to simulate the interaction mode between the hosts and the guests.

A convenient method for synthesis of trans -4-cyclohexyl-L-proline

Abstract A convenient method for the synthesis of the fosinopril precursor, trans -4-cyclohexyl- l -proline 1 , has been developed. A highly stereoselective alkylation of N -benzyl-pyroglutamic acid 2 with 3-bromocyclohexene at −10°C and subsequent hydrogenolysis afforded the trans -4-cyclohexyl- l -pyroglutamic acid 4 . The esterified 4 was sulfurized with Lawessons reagent, desulfurized with Raney-Ni and hydrogenolytic cleavage of the benzyl protecting groups to afford 1 with 93% e.e.

Facile Synthesis of C3-Symmetric Tripodal β-Hydroxy Amide Ligands and Their Ti (IV) Complex-Catalyzed Asymmetric Addition of Diethylzinc to Aldehydes

Chiral c-3-symmetric tripodal tris(beta-hydroxy amide) ligands have been conveniently synthesized via the reaction of 1,3,5-benzenctricarboxylic chloride and chiral amino alcohols, and the corresponding tris(amino alcohol) ligands were obtained via the borane reduction of amides. the asymmetric diethylzinc addition to various aldehydes catalyzed by these chiral ligand-ti (iv) complexes gave modest enantioselectivities.