Propenoic acid, 2- hydrogenation

Homogeneous catalysts may also be effective in the hydrogenation of sulfur-containing compounds. (Z)-2-Benzamide(acetamido)-3-(2-thienyl)-2-propenoic acid was reduced in 100% yield and 78% enantiomeric excesses over Rh(I)-DlOP catalysts (25),... 

Ruthenium complexes of (129) and (130)336 were investigated for the asymmetric hydrogenation of prochiral 2-R-propenoic acids (Scheme 62a) rhodium complexes of these ligands were used for hydrogenation of acetoamido-cinnamic acid methyl ester (Scheme 62c) and hydrogenation of acetophenone-benzylamine (Scheme 62b). The results obtained with these... 

Prochiral imines can be hydrogenated to the corresponding amines with extremely high enan-tioselectivities in H20/ethyl ethanoate biphasic systems, using Rh1 complexes of sulfonated phosphines 342 The cationic rhodium complex [Rh(NBD)(131)]+ was an active catalyst for hydrogenation of 2-ethanamido-propenoic acid in aqueous solution.343... 

Prochiral derivatives of propenoic acid were reduced by hydrogen transfer from aqueous solutions of M[HCOO] (M = K+, Na+ and [NH4]+) catalyzed by Rh1 complexes of (117) or the tetrasulfonated cyclobutanediop (132) 345 Aldehydes were reduced in a phase transfer catalytic system having [RuCl2(PPh3)3] as the catalyst in the organic phase (for example chlorobenzene) and the hydrogen donor (Na-methanoate) in the aqueous phase.346... 

A second way (method ) uses a chiral auxiliary by converting the propenoic acid into an amide. Catalytic hydrogenation with the achiral catalyst 5 shows a modest diastereoface selection, 6/7 1.9 1. Both methods lead to the (5) configuration at C-2 and combining the effects, i.e., chiral auxiliary with ( + )-3 ( matched combination ), increases the (5) selectivity from 11 1 to 16 1 (calculated value 11 x 1.9 = 21 1). In contrast, the use of the chiral auxiliary with (—)-3 counteracts the inherent (S) induction in the starting amide ( mismatched combination ) and favors (R) induction, 6/7 1 4.5 (calculated value 1.9 11 = 1 6). 

The propene ion is one system in which determination of isotope effects is hampered by hydrogen randomisation. Nevertheless, deuterium isotope effects upon ion abundances following El have been obtained by making allowances for the extent of hydrogen randomisation [see Sect. 7.5.1(f)]. For hydrogen atom elimination, the isotope effect/H//D has been put at 1.7—2.0 for source reactions [372] and 2.3—3.0 and 3.6 (first and second field-free regions, respectively) for metastable ions [510]. For hydrogen atom elimination from propenoic acid ions, the isotope effect /H//D has been put at 4.3 for metastable ions [587]. 

The next higher homologous side-chain carboxyl acid is the one in which the side chain has three carbon groups, CeHs—CH2—CH2— COOH. It is, therefore, beta-phenyl propionic acid or i-carboxy 2-phenyl ethane. It is commonly known as hydrocinnamic acid because of its relation to cinnamic acid as the hydrogenated or reduction product. In the aliphatic series we have two acids, one, propanoic acid or propionic acid, the other propenoic acid or acrylic acid. They are related to each other as corresponding saturated and unsaturated compounds (p. 172). The latter, acrylic acid, yields propionic acid on reduction by the addition of two hydrogen atoms and the conversion of the unsaturated chain into a saturated one. 

The asymmetric catalytic hydrogenation of 2-(6 -methoxy-2 -naphthyl)propenoic acid to (S)-naproxen was monitored in both methanol- and C02-expanded methanol.f The catalyst used was [dichloro-(S)-(-)-2,2 -bis(diphenyl-phosphino)-1, l -binapthyl]ruthenium(II). Addition of CO2 to the methanol produced strong retardation of the reaction rate. An average reduction in enantioselectivity of 6%i was observed compared to that in methanol. The enantioselectivity was found to increase as the temperature decreased in both neat methanol and C02-expanded methanol systems, indicating that the underlying mechanisms were similar. Insufficient oxygen removal may have prevented the... 

Normal elimination of hydrogen and bromine would then be possible, to give propenoic acid. Structure 5.1. 

Duraphos OAP. See 2-Ethylhexyl phosphate Duraphos PA 70%. See Phosphorous acid Duraphos TLP. See Trilauryl phosphite Duraphos TPP. See Triphenyl phosphite Durastrength 200. See 2-Propenoic acid, 2-methylmethyl ester, polymer with 1,3-butadiene and butyl 2-propenoate Duratex. See Hydrogenated cottonseed oil Durax Rodform] Durax . See N-Cyclohexyl-2-benzothiazolesulfenamide Durazone 37. See 2,4,6-Tris-(N-1,4-dimethylpentyl-p-phenylenediamino)-1,3,5-triazine... 

Sodium cyanoborohydride is an effective reagent for the reduction of P-amino-propenoic acid derivatives. Reaction of benzylamine with ethyl acetoacetate gave 1.124 and reduction with cyanoborohydride led to ethyl N-benzyl-3-aminobutanoate, 1.125When R-phenethylamine was used in place of benzylamine, the amino acid product showed asymmetric induction (2-28% ee, see chapter five) after the phen-ethyl group was removed by treatment with hydrogen and Pd(OH)2 on carbon. ... 

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