Mandelic add

Chorionic gonadotropin. Follicle stimulating hormone Urea, Uric add. Bilirubin, Cortisol, n-Maimitol. n-Glucose, Sodium pyruvate, 4-hydroxy-3-methoxy mandelic add, 4-Nitro-phenol, 17 Amino adds in HQ, Angiotensin-I, Tripahnitin, Bone meal (8 elements), Bone ash (8 elements), lithium carbonate Luteinizing hormone. Thyroid stimulating hormone... 

The present two-step procedure for preparation of the racemic diphenylethylenediamine is significantly shorter and more suitable for scale-up than that described in the literature.4 The resolution of the racemate has also been reported using the commercially available enantiomers of mandelic add. ... 

In the case of benzal chloride, the carboxylation in conventional diaphragm systems fails, leading to poor yields in phenylacetic and mandelic add [180], At an Al anode, carboxylation occurs because the self-esterification of the first carboxylate anion onto the second chloride group is hindered by the formation of Al complex salts [181]. Yields of phenylmalonic and chlorophenylic acetic acids up to 30% each have been obtained [178],... 

Benzyl (S)-l,2,3,4-Tetrahydroisoquinoline-3-carboxylate (S)-Mandelic Add Salt (40A) and Benzyl (R)-l,2,3,4-Tetrahydroisot uinoline-3-carboxylate (f )-Mandelic Acid Salt (40B) [791... 

This compound was prepared in the same manner as (R)-Tic, using benzyl (S)-1,2,3,4-tetra-hydroisoquinoline-3-carboxylate (S)-mandelic add salt (40A) as starting material yield of (S)-33 920 mg (81%) mp 322-327 °C. 

Figure 1 Fischer projections of (/t)- and (S)-enantiomers of lactic add (X = Me), mandelic add (X = Ph), glyceric acid...

Homatropine is a synthetic parasympatholytic representing the ester of tropine and mandelic add (Fig. 1). This drug antagonizes acetylcholine on MR and is thus used as mydriatic with less detrimental paralytic effects on ciliary eye muscle than atropine but showing faster and shorter action [1,33], Therefore, it belongs to the WHO list of essential medicines as mydriatic eye drops representing an alternative to atropine [41],... 

Thus, in terms of stereochemical theory, the minimal requirement for the differentiation of enantiomers by a chiral reagent is a one-point approach rather than a three-point attachment . This idea is illuminated by the data cited earlier for the heats of neutralization between the base, a-phenylethylamine, and mandelic add. Here the reaction does not involve a covalent bond formation rather it is an ionization leading to an electrostatic situation. For the neutralization of (R )-base with (/ )-acid, — AH = 7.630 0.013 kcal/mol for (/ )-base with (S)-acid, —AH = 7.431 0.014 kcal/mol—a significant difference of approx. 0.2 kcal/mol. 

Deracemization of mandelic add with the combined action of two enzymes has been reported. rac-MandeUc acid is acylated by a Pseudomonas sp. lipase in diisopropyl ether. After solvent removal the mfacture of mandeUc acid enriched in the R-form and the 0-acetyl derivative of the S-configuration are subjected to the mandelate racemase-catalyzed racemization in aqueous buffer. In these conditions only the non-acetylated hydroxy acid is racemized. In order to obtain (S)-0-acetylmandelic acid in an 80% isolated yield and a >98% e.e. the process must be repeated four times [9]. 

Inhibition of the Ce(TV)-oxalate oxidation by oxalate itself is interpreted in terms of the formation of higher complexes at high oxalate concentrations. If the 1 1 complex is the most reactive, its concentration is decreased when higher complexes are formed. For 10 M Ce(IV) the maximum rate of reaction with oxalate occurs with an oxalate concentration of 2 x 10 M. It seems reasonable to presume the formation of a Ce(IV) complex as the reactive intermediate in the oxidation of several other substances such as citric acid, mandelic add, benzilic acid, and polyamino-polycarboxylic acids. ... 

Several derivatives of mandelic add have been used as CDAs for the resolution of chiral alcohols as the corresponding esters. Thus, in a study of the steric course of the cytochrome P-450-mediated hydroxylation of phenylethane (ethylbenzene), White et al. derivatized the enzymatically formed 1-phenylethanols with (S)-O-propionylmandelyl chloride, [36], and separated the diastereomeric derivatives by GLC (153). Comber and Brouillette synthesized the enantiomers of carnitine via derivatization of a racemic precursor alcohol with (R)- or (S)-a-methoxyphenylacetic [(0)-... 

Frankland and Price were the first to attempt the resolution of alcohols (and adds) by fractional crystallization of their solid esters. The isomeric solid esters formed from Z-s-butylcarbinol and di-dibenzoyl-glyceric acid failed to separate on crystallization the correspondinjg di-alcohol-i-add ester was liquid. Marckwald and McKenzie effected partial resolutions of di-mandelic add and related adds with i-menthol and d-bomeol, and of di-2-octanol with d-tartaric add, but did not develop a satisfactory method for resolving alcohols. Later investigators, however, have employed the following resolving agents in several more or less successful resolutions of certain alcohols (a) i-menthyl isocyanate, (b) d-camphoric add, (c) d- or i-mandelic add, (d) d- or... 

Example Mandelic Add from Benzaldehyde1 (a) Mandelic Nitrile... 

Like all compounds of this class, it exists in two different space modifications, which bear the same relation to each other as does an object and its image, and owing to their power of revolving the plane of polarisation, are called dextro- and laevo-mandelic acids. The acid obtained in the above synthesis is optically inactive since, in the synthesis of compounds with an asymmetric carbon atom from inactive substances, an equal number of molecules of the dextro- and laevo-varieties are always obtained, which, in the above case, unite to form the inactive- so-called, para-mandelic add. But, by different methods, the active adds can be obtained from the inactive modifications. If, e.g., the dnchonine salt of para-mandelic add Is allowed to crystallise, the more difficultly soluble salt of the dextro-add separates out first, and then, later, the laevo-salt crystallises. By treatment with acids, the free active acids may be obtained. 

Fig. 7.9 Deracemization of ( )-mandelic add via a Upase-mandelate racemase two-enzyme system Pseudomonas sp. Upase-catalysed O-acylation of ( )-mandelic acid and by mandelate racemase catalysed racemisation of the remaining unreacted (/J)-mandelic acid [75].

ATCC 8750. An isolated yield of 94% of the enantiomerically pure mandelic add was obtained, indicating that a dynamic resolution process is occurring. 

The cycloaddition of chiral nitrile oxides to achiral alkenes generally results in a low degree of induced stereoselection125,129-135,355. Regardless of the source of the chiral dipole sug-ars129,130 13 >, glyceraldehyde131 -133 or mandelic add 13 t, diastereomeric ratio values of less... 

The enantiomers of 2-cyclohexy(-2-hydroxy acetic add 12 and their esters are conveniently obtained from the corresponding mandelic adds (or derivatives) by catalytic hydrogenation with a platinum catalyst16 17. The methyl ester has been used for the enantioselectivc protonation of lactone enolates (Section D.2.1.) and the chiral diene prepared analogously to the O-methylmandclic acid derivatives11-13 described in the preceding section in diastereoselective Diels-Alder reactions (Section D. 1.6.1.1.1.). 

---