Mandelic acid, />-bromo

Malonic ester syntheses, 30, 7 Malononitrile, 37, 53 Malonyl dichloride, 33, 20 Mandelic acid, 36, 3 Mandelic acid, />-bromo, 35,11 Mannich reaction, with acetone, 37,18 Mercaptoacetaldehyde, diethyl ACETAL, 35, 51... 

Some physical properties and structural features of the normal tetramandelate have been reported. The solubility of the 1 4 mandelato complex in 2 Jlf perchloric acid was determined to be 7.8 x 10" mole/ liter (444), and was found to fall slowly with increasing pH to a minimum of 4 X 10 at pH 3.1, after which it then rose. The change in solubility was accompanied by a change in composition which involved the formation of metal oxo species. In 1958, R. W. Stromatt (540) concluded on the basis of infrared spectroscopy, that the tetramandelates exist as discrete 8-coordinate molecular species. This would seem to be supported by the fact (24) that an organic-soluble species can be extracted from aqueous solutions containing (1.0 to 8) x 10 mole/liter zirconium(IV) in 1 M perchloric acid with an isopentyl alcohol solution of p-bromo-mandelic acid. The normal tetramandelate precipitated from aqueous solution at the usual concentration conditions, however, is very insoluble... 

C2-homologizati on of sugars with, 264-265 Acetamide, JV-bromo- (AcNHBr, NBA) bromohydrination with, 275-276, 287 Acetaminophen (= paracetamol), 301 Acetate, piperidinium cat. for aldol add., 82 —, sodium a-epimerization of ketones, 277 opening of oxiranes, 282 Acetic acid, anhydride (AcfO) protection with. See Protection Pummerer rearr. with, 51, 265 —, esters (See also Protection of hydroxy groups) C-H acidity, 10 1-methylethenyi ester pr., 174 transenolization, 58 —, bromo-, esters pr., 179 a2-synthon, 19, 65, 309 d2-synthon, 19, 301 —, chloro-, esters pr., 179 hydantoins from, 308 —, cyano-, esters pr., 177 pyrrolines from, 298 —, (dialkoxyphosphinyl)-, esters pr 188 Wittig-Horner olefinations, 267, 282 —, diazo-, ethyl ester pr, 176, 178 cyclopropanes from, 74—75 —, dichloro- deblocking of pixyl ethers, 342 —, hydroxy-, esters pr., 176 —, hydroxyphenyl-, (S)- (l-mandelic acid) ... 

R,S-thiorphan D.L-4-Mandclic acid D,L-4-bromo-mandelic acid D,L-4-chloro-mandclic acid D,L-3-hydroxy-mandelic acid D,L-4-hydroxy-mandelic acid... 

Hydroxy-acids.—A full report has been published on the preparation of chiral a-hydroxy-acids in optical yields of up to 98% from a, -unsaturated acid chlorides by sequential N-acylation of an optically pure a-amino-acid, bromo-lactonization, dehydrobromination, and hydrolysis " (2, 23). Enolates of /-menthyl mandelate can be alkylated in ca. 50% yield with typical enantiomeric excesses of less than 40%, An elegant use of the prophos ligands in rhodium(i)-catalysed asymmetric hydrogenation (see 3,322) is in the preparation of all twelve isomers of chiral methyl chiral lactic acid the method is illustrated for one isomer in Scheme 5. The other isomers are obtained by changing the order of introduction of H, D, and T and the chirality (i.e. R or S) of the prophos ligand. 

In the second approach, new cyclic diester monomers, 35 -(benzylox-ymethyl)-6S-methyl-l,4-dioxane-2,5-dione (BMD) consisting of both L-lactate and a-O-benzyl-glycerate units and 3S-phenyl-6S-methyl-l,4-dioxane-2,5-dione (PMD) consisting of mandelate and lactate units, have been synthesized by base-catalyzed cyclization of the coupling products of the corresponding hydrojyl-acids with 2-bromo-propionyl chloride. These... 

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