S 4-hydroxy

Modification of the Carbohydrate Ring Substituents. Replacement of hncomycin s 2-hydroxy group by methoxy or by hydrogen (74), or inversion of the configuration of the hydroxy group at C-4 or at C-2 destroys activity (75). 

An aldol addition of doubly deprotonated (S )-2-hydroxy-l,2,2-triphenylethyl propanoate (13) has been applied in a total synthesis of dolastatin72 . 

Dithiokohlensaure-0-athylester-S-(2-hydroxy-phenylester) 54 g (0,5 Mol) 2-Amino-phenot in 600 ml Eiswasscr und 125 ml konz. Salzsaure diazotiert man mit einer Losung von 35 g (0,5 Mol) Natriumnitrit in 340 ml Wasser bei 0°, tropft die Diazoniumsalz-Losung langsam unter Riihren zu der Losung von 480 g (3 Mol) Kalium-O-athyl-dithiocarbonat in 375 ml Wasser bei 75°, laBt 12 Stdn. stehen, extrahiert mit Ather, wascht die organ. Phase mit Wasser und Natriumcarbonat-Losung aus, trocknet iiber Natriumsulfat und destil-liert den Ather ab. 

C[gH 5N04 136465-82-2) see Saquinavir [S-(S, S )]-[2-hydroxy-3-oxo-l-[(phenylthio)metbyl]pro-pyl]carbamic acid phenylmethyl ester... 

D(-)-2-(4-hydroxyphenyl)glycyl chloride hydrochloride see under D-/ -hydroxyphenylglycyl chloride hydrochloride 7-hydroxy-7-phenylheptanoic acid (CijHigOi 103187-18-4) see Seratrodast [/ -(/J, S )]-[2-hydroxy-l-[[(phenylmethoxy)amino]carbo-nyl]propyl]carbamic acid l,l carbonyl]amino]hep-tanoic acid... 

S (2)-hydroxy-3-butenenitrile from acrolein and HCN trans hydrocyanation using, for instance, acetone cyanohydrin Hydrolysis of nitriles to amides, e.g. acrylonitrile to acrylamide Isomerization of glucose to fructose Esterifications and transesterifications Interesterify positions 1 and 3 of natural glycerides Oxidation of glucose to gluconic acid, glycolic acid to glyoxalic acid... 

Park et al.34,35 have used (S)-2-hydroxy-2 -(3-phenyl-uryl-benzyl)-l,l -binaphthyl-3-carboxaldehyde for conversion of L-amino acids or peptides into D-amino acids [17]. 

Dipolar cycloadditions of 2-tert-butoxycarbonyl-1 -pyrroline A -oxide (627) with several chiral acrylamides (634a-f) (Scheme 2.276) followed by hydrogenolysis of cycloadducts (635) and (636) has been used in the synthesis of enantiopure tert-butyl (2RJ R)- and (2.S. 7a.S )-2-hydroxy-3-oxo-tetrahydro-l II -pyrrolizine-7a(5// )-carboxylates, useful intermediates for the synthesis of Gly-(s-cis)Pro dipeptide mimetic (790). 

Nature uses enantioselective transfer hydrogenation to reduce metabolites, for example pyruvate to give (S)-lactic acid and 2-ketoglutarate to give (S)-2-hydroxy -glutarate. The reaction is reversible and the equilibrium position depends on the concentration of the species. The enzyme catalysts are named dehydrogenases, and they employ a soluble cofactor or hydride acceptor called NAD(P) in its oxi-... 

R)-(+)-1,1,2-Triphenyl-1,2-ethanediol is available from methyl3 and ethyl4 (R)-(-)-mandelate by treatment with phenylmagnesium bromide. The synthesis of (R)-(+)-2-hydroxy-1,2,2-triphenylethyl acetate [(R)-HYTRA] has been reported previously by the submitters.5 6 (S)-(-)-2-Hydroxy-1,2,2-triphenylethyl acetate is available according to this procedure starting from the enantiomeric methyl (S)-(+)-mandelate or (S)-(+)-... 

Scheme 8.1 Chemoenzymatic synthesis of (S)-2-hydroxy-2-methylhutyric acid by using the docking protecting group concept...

Fechter, M.H., Gruber, K., Avi, M., Skranc, W., Schuster, C., Pbchlauer, P., Klepp, K.O. and Griengl, H., Stereoselective biocatalytic synthesis of (S)-2-hydroxy-2-methylbutyric acid via substrate engineering by using thio-disguised precursors and oxynitrilase catalysis. Chem. Eur. J., 2007,13, 3369. 

CYTOCHROME P-450 REDUCTASE DIHYDROOROTATE OXIDASE FMN ADENYLYLTRANSFERASE GLUTAMATE SYNTHASE GLYCOLATE OXIDASE (S)-2-HYDROXY-ACID OXIDASE l-LACTATE DEHYDROGENASE (CYTOCHROME)... 

ACID-BASE RELATIONSHIPS OXYGEN, OXIDES 0X0 ANIONS d-2-HYDROXY-ACID DEHYDROGENASE (S)-2-HYDROXY-ACID OXIDASE 3-HYDROXYACYL-CoA DEHYDROGENASE /3-HYDROXYACYL THIOESTER (or, ACP) DE-HYDRASE... 

S)-leucine, and (S)-sec-butyl-(R)-oxirane from (2S,3S)-isoleucine, respectively. This useful three-step route complements the synthesis of (S)-alkyloxiranes from (S)-2-araino acids via (S)-2-hydroxy acids,with retention of configuration at the stereocenter. 

Therefore, in principal, condensation of a primary amine with an enantiomerically pure ketone should allow asymmetric synthesis of a-substituted primary amines. This approach has been applied to the synthesis of a-amino acids, for example, using the imine prepared from a-amino esters and (l.S, 2,S ,5,S )-2-hydroxy-3-pinanone, via an amino-substituted ester enolate anion with some success39 40. Application of this approach to simple primary amines has seldom been reported. 

The potential of benzoylformate decarboxylase (BFD, E.C. 4.1.1.7) to catalyze C-C bond formation was first reported by Wilcocks at al. using crude extracts of Pseudomonas putidsL [50]. They observed the formation of (S)-2-hydroxy-l-phenylpro-panone (S)-2-HPP when benzoyl formate was decarboxylated in the presence of acetaldehyde. Advantageously, aldehydes - without a previous decarboxylation step - can be used instead of the corresponding more expensive a-keto acids [51]. We could show that BFD is able to bind a broad range of different aromatic, heteroaromatic, and even cyclic aliphatic and conjugated olefinic aldehydes to ThDP before ligation to acetaldehyde or other aldehydes (Table 2.2.7.3) [52]. 

Fig. 7. Effect of modifying pH on EDA of MRNi (O) (S)-manderic acid MRNi (33) ( ) (S)-2-hydroxy-3-phenyl-propionic acid-MRNi (33) ( ) (S)-aspartic acid-MRNi (19) (A) (R.R),tartaric acid-MRNi (25). Modifying conditions 0°C. Reaction conditions MAA (neat), 60 C, 80-100 kg/cm2.

The absorption modes of (S)-3-phenyl-2-hydroxypropionic acid, (S)-3-phenyl-2-aminopropionic acid, and (S)-alanine adsorbed on a nickel plate or RNi were studied by Suetaka s group (71, 72). From the measurement of infrared (IR) dichroism in the reflection spectrum, the molecular orientation of the modifying reagent was deduced. Figures 19-21 show molecular orientations of (S)-2-hydroxy-3-phenylpropionic acid on a nickel plate and (R)-alanines on RNis modified at 5° and 100°C, respectively. 

Effect of Cation Used for the Adjustment of Modifying pH on EDA of (S)-2-Hydroxy isovaleric Acid-MRNi°... 

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