Synthesis of (2R,5S)- and (2S,5S)-2-carboxy-1,4-diaza[4.3.0]bicyclononane as building blocks for the synthesis of new potential HIV protease inhibitors
A procedure for the preparation of optically active (2R,5S)- and (2S,5S)-2-carboxy-1,4-diaza-[4.3.0]bicyclononane is described. The method is based on the reduction of diketopiperazines obtained from cyclization of Pro-L-Ser or Pro-D-Ser and occurs withou
Chiral Ligands Containing Heteroatoms. 11. Optically Active 2-Hydroxymethyl Piperazines as Catalyst in the Enantioselective Addition of Diethylzinc to Benzaldehyde
Starting from enantiomerically pure serine, a series of (2R,5S) and (2S,5S)-2-hydroxymethyl-5-alkyl piperazines 1-5 were prepared in good yields without any racemization.The use of these compounds as chiral catalysts for the enantioselective addition of d