Catalytic asymmetric hydrogenation of alpha-amino-beta-keto ester hydrochlorides using homogeneous chiral nickel-bisphosphine complexes through DKR.

Homogeneous chiral nickel-bisphosphine complexes catalyze the asymmetric hydrogenation of alpha-amino-beta-keto ester hydrochlorides through dynamic kinetic resolution to efficiently afford anti-beta-hydroxy-alpha-amino esters with high diastereo- and enantioselectivities.

Determination of 3(1)-stereochemistry in synthetic bacteriochlorophyll-d homologues and self-aggregation of their zinc complexes.

Zinc complex of methyl 3(1)-octadecyl-bacteriopheophorbide-d was prepared from modification of naturally occurring chlorophyll-a. The 3(1)-epimerically pure samples were obtained by HPLC separation and their stereochemistry including the absolute configuration at the secondary alcoholic 3(1)-position was determined by combination of esterification to methoxy(trifluoromethyl)phenylacetate and NMR spectroscopy (Mosher's method). Both the epimers were monomeric in a polar organic solvent and self-aggregated in a non-polar solvent to give oligomers as well as dimers possessing red-shifted visible absorption bands. Visible spectra of the non-polar organic solutions were dependent upon the 3(1)-chirality and such a diastereoselective control on the self-aggregation led to the formation of self-aggregates with different supramolecular structures.