Reference

Amino acids in high optical yield via catalytic hydrogenation

Amino acids in high optical yield via catalytic hydrogenation. Stille, John K. (Polymer Sciences Corp., USA). U.S. US 4424312 A 3 Jan 1984, 11 pp. (English). (United States of America). CODEN: USXXAM. CLASS: IC: C08F008-42; C08F220-34. NCL: 525274000. APPLICATION: US 81-243747 16 Mar 1981. DOCUMENT TYPE: Patent CA Section: 34 (Amino Acids, Peptides, and Proteins) Section cross-reference(s): 29, 78 The asym. hydrogenation of N-acyl dehydroamino acids was catalyzed by Rh complexes of copolymers contg. chiral pyrrolidinephosphines I or II. Thus, hydroxyproline III (Boc = Me3CO2C, R = CO2Et) was reduced by LiBH4 in THF to give 81% III (R = CH2OH), which was tosylated to give the di-o-tosyl deriv. (89%), which was treated with NaPPh2 to give 65% pyrrolidinephosphine IV (R1 = Boc). The latter was Boc-deblocked by CF3CO2H to give 97% IV (R1 = H), which was acylated with CH2:CHCOCl to give 89% I. I was copolymd. with hydroxyethyl methacrylate and ethylene dimethacrylate to give the corresponding copolymer, which was treated with m-dichlorobis(1,5-hexadiene)dirhodium (I) to give the corresponding Rh-polymer complex, which catalyzed the asym. 5469-45-4 and 17355-23-6 are just another two chemicals used in this study. hydrogenation of PhCH:C(NHAc)CO2H to give (R)-PhCH2CH(NHAc) CO2H with an optical yield of 91%. .