the dioxolane ring had a small effect on the asymmetric induction by DIOP in the hydrogenation. Modification at the phosphino group affected the stereocontrol by the ligand and the unsymmetrical DIOP with di-2-naphthylphosphino group gave higher optical yields than (−)-DIOP for the hydrogenation of α-acetamidocinnamic acid and dehydrodipeptides.
New chiraldiphosphinites were prepared starting from (+)-diethyl tartrate. The asymmetrichydrogenation of dehydroamino acids, itaconic acid and dehydrodipeptides was studied using Rh(I)-diphosphinite catalysts. In the hydrogenation of dehydroamino acid derivatives, an introducion of ω-(dimethylamino)alkyl group in the ligands did not raise the optical yield. By the use of Rh(I)-diphosphinite having
Asymmetric Hydrogenation of Dehydrodipeptides with Rhodium(I)–Chiral Diphosphinites. Selective (<i>S</i>,<i>S</i>)- and (<i>R</i>,<i>R</i>)-Product Formation by Double Asymmetric Induction
stereoselectivities, depending on the chiral center of the substrates. This result was ascribed to the electrostaticinteractionbetween the ligand and substrate. POP’s without ω-(dimethylamino)alkyl group gave (R,R)-product for (R)-substrate in a high stereoselectivity by the steric effect between the ligand and substrate, while for (S)-substrate, (S,S)-product was obtained in a low stereoselectivity.
Diastereoselective hydrogenation of N-acetyldehydrodipeptides
作者:V. K. Latov、A. I. Vinogradova、M. B. Saporovskaya、V. M. Belikov
DOI:10.1007/bf00949793
日期:1982.3
SYNTHESIS OF OPTICALLY ACTIVE<i>N</i>-[(<i>N</i>-ACETYL)-α-AMINOACYL]-β-AMINO ALCOHOLS BY HOMOGENEOUS AND HETEROGENEOUS ASYMMETRIC HYDROGENATIONS
作者:Iwao Ojima、Momoko Yatabe
DOI:10.1246/cl.1982.1335
日期:1982.9.5
Asymmetric hydrogenations of N-(N-acetyldehydrophenylalanyl)-β-amino alcohol benzyl ethers were carried out by using either rhodium complexes with chiral and achiral phosphines or 10% palladium on carbon. The effects of the chiral center in the β-amino alcohol moiety on simple as well as double asymmetric induction are described.