Optically active phosphines of formula (I) are new: A-P(B)-CH2.CH2-P(B)-A (I) (A and B are opt. substd 1-12C alkyl, 4-7C cycloalkyl or aryl abut A and B must be different and not interfere with the steric conditions around the C atoms). Catalysts for homogeneous reactions comprise (a) Rh, Ir or Ru and (b) 0.5-2 moles per mole metal of (I). Processes for stereoselective hydrogenation of beta-substd alpha-acylamidoacrylic acids (II) or their salts, esters and amides using these catalysts are also claimed. The tetrafluoroborate of cycloocta-1,5-diene 1,2-bis(o-anisylphenyl phosphino)ethane rhodium and solns contg bis (cycloocta-1,5-diene) dichlorodirhodium and 1,2-bis(o-anisylphenylphosphino)ethane. wherein the phosphine is optically active, are also new. The catalysts contg (I) as ligands agive hydrogenations of high stereospecificity. Prods include alanine, valine, 3-(3,4-dihydroxyphenyl)-L-alanine (i.e L-DOPA) and esp. substd phenylalanines obtd by reducing (II) produced by hydrolysis of azolactones during Erlenmeyer's synthesis.
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