3.4- dihydroxy carboxylic acid

Compound A is a cyclic acetal and undergoes hydrolysis in aqueous acid to produce acetaldehyde, along with a dihydroxy carboxylic acid. 

The completion of the total synthesis is described in Scheme 78. The Wittig reaction of 552 and 538 effected the coupling, and subsequent deprotection of TMS with KF afforded 41,42-dihydroxy carboxylic acid 553. Yamaguchi conditions effected macrolactonization of 553 in high yield and complete deprotection of the silyl groups afforded 4b and 554 in a ratio of 1 3. Treatment of (-)-23-epi-altohyrtin... 

Step two of the analysis is performed when the yellow color has disappeared. Here dilute sodium hydroxide solution R is added dropwise, and an intense blue color is produced caused by a complex between the dihydrox-fumeric acid and the iron(III) ions. No structure of this complex has apparently been published. It is different from the general complexes normally formed between the aliphatic dihydroxy carboxylic acid wi iron(III), since they are often yellow or violet and have an optimum in the pH region below neutrality. One could suspect that an enolization of the dihydroxfumeric acid is responsible for the blue colored complex. 

At the time the ester 173 was disclosed, a demand came for stereoselective acetate aldol reactions in the development of HMG-CoA reductase inhibitors, which feature unbranched p,8-dihydroxy carboxylic acids or the corresponding 8-lactones as the pharmacophore. Thus, a series of those inhibitors were synthesized, partly in large scale, by using the HYTR A method [99], and some of them made it to best-selling drugs like atorvastatin [99a-d], fluvastatin [99e, f], and lovastatin [99g] that were developed by the companies Parke-Davis, Sandoz, and Merck, respectively (Scheme 4.38). 

Ethers of benzenepentol have been obtained by Dakin oxidation of the appropriately substituted acetophenone. Thus, the oxidation of 2-hydroxy-3,4,6-ttimethoxyacetophenone and 2-hydroxy-3,4,5-ttimethoxyacetophenone with hydrogen peroxide ia the presence of alkali gives l,2-dihydroxy-3,4,6-ttimethoxybenzene and l,2-dihydroxy-3,4,5-ttimethoxybenzene, respectively further methylation of these ethers yields the pentamethyl ether of benzenepentol (mp 58—59 degC) (253). The one-step aromatization of myoinositol to produce esters of pentahydroxybenzene is achieved by treatment with carboxylic acid anhydrides ia DMSO and ia the presence of pyridine (254) (see Vitamins). 6-Alkyl- or... 

Aluminum salts of carboxylic acids, aluminum carboxylates, may occur as aluminum tricarboxylates (normal aluminum carboxylates), Al(OOCR)2 monohydroxy (monobasic) aluminum dicarboxylates, (RCOO)2Al(OH) and dihydroxy (dibasic) aluminum monocarboxylates, RCOOAl(OH)2. Aluminum carboxylates are used in three general areas textiles, gelling, and pharmaceuticals. Derivatives of low molecular weight carboxyUc acids have been mainly associated with textile appHcations those of fatty carboxyUc acids are associated with gelling salts and more complex carboxylates find appHcations in pharmaceuticals. 

Benzo[b]thiophene-2-carboxylic acid, 4,7-dihydroxy-synthesis, 4, 928... 

The tri/luorovinyloxy group is cleaved by potassium persulfate [37J The pnmanly formed dihydroxy compound undergoes spontaneous hydrolysis with the formation of carboxylic acid (equation 29)... 

ZN(C)153, 00ZN(C)323, 00ZN(C)857, 01MI2, 01MIP4, 01TL5849). 5-Amino-8,9-dihydroxy-2,3-dihydro-l//-pyrimido[l,2-u]quinoline-3-carboxylic acid moiety 4 was also identified as a chromophoric moiety of certain... 

Hydrogenolytic cleavage of isoxazolines has also proved useful in preparation of -dihydroxy ketones and -hydroxy carboxylic acids (47). The isoxazolines were prepared by a [3 -1- 2] cycloaddition. 

Chemical Name 7-chloro-2,3-dihydro-2,2-dihydroxy-5-phenyl-1 H-1,4-benzodiazepine-3-carboxylic acid dipotassium salt... 

It was anticipated that fragments 147 and 214 could be united through an amide bond linking the nitrogen atom of the latter with C-8 of the former. Indeed, the active ester formed by treatment of carboxylic acid 147 with 1,3-diisopropylcarbodiimide and 1-hydro-xybenzotriazole reacts efficiently with amine 214 to afford dihydroxy amide 215 in 95 % yield. This convergent union creates a molecule that possesses all but two carbon atoms of the natural product. 

Polyesters. The polycondensation prods of di-carboxylic acids with dihydroxy alcohols. 

The pendant hydroxy groups of ethylene oxide-propylene oxide copolymers of dihydroxy and trihydroxy alcohols may be sulfurized to obtain a sulfurized alcohol additive. This is effective as a lubricant in combination with oils and fats [387,533]. The sulfurized alcohols may be obtained by the reaction of sulfur with an unsaturated alcohol. Furthermore, fatty alcohols and their mixtures with carboxylic acid esters as lubricant components [1286] have been proposed. 

The highly ordered cyclic TS of the D-A reaction permits design of diastereo-or enantioselective reactions. (See Section 2.4 of Part A to review the principles of diastereoselectivity and enantioselectivity.) One way to achieve this is to install a chiral auxiliary.80 The cycloaddition proceeds to give two diastereomeric products that can be separated and purified. Because of the lower temperature required and the greater stereoselectivity observed in Lewis acid-catalyzed reactions, the best diastereoselectivity is observed in catalyzed reactions. Several chiral auxiliaries that are capable of high levels of diastereoselectivity have been developed. Chiral esters and amides of acrylic acid are particularly useful because the auxiliary can be recovered by hydrolysis of the purified adduct to give the enantiomerically pure carboxylic acid. Early examples involved acryloyl esters of chiral alcohols, including lactates and mandelates. Esters of the lactone of 2,4-dihydroxy-3,3-dimethylbutanoic acid (pantolactone) have also proven useful. 

Displacement of the 3-hydroxyl group of 74 was carried out with Et2NSF3 (DAST) (DAST - diethylaminosulfur trifluoride) in dichloromethane. The expected fluorinated product 75 on treatment with aqueous perchloric acid led to regioselective epoxide ring opening to give 76, which on treatment with hydrazine hydrate at 100 °C for 18 h yielded 3,4-dihydroxy-8-oxo-octahydropyridazino[l,6-r/][l,2,4]triazine-l-carboxylic acid phenylamide 77 (Scheme 3) <1997T9357>. 

Unsaturated polyesters are prepared through a classical esterification process. Typically, a dihydroxy compound, or mixtures of dihydroxy compounds, are treated with maleic anhydride and/or together with other dicarboxylic acids such as aromatic or aliphatic dicarboxylic acids under elevated temperature to remove the water produced during esterification process. Although various catalysts will catalyze this esterification reaction, there is enough carboxylic acid in the mixture so that it is not necessary to add extra catalyst. 

Chorazepate Chorazepate, 7-chloro-2,3-dihydro-2,2-dihydroxy-5-phenyl-1H-1,4-benzo-diazepin-3-carboxylic acid (5.1.34), which is used in the form of a dipotassium salt, is synthesized by yet another interesting synthetic scheme. 2-Amino-5-chlorobenzonitrile is used as the initial compound, which upon reaction with phenyhnagnesiumbromide is transformed into 2-amino-5-chlorbenzophenone imine (5.1.32). Reacting this with amino-malonic ester gives a heterocyclization product, 7-chloro-l,3-dihydro-3-carbethoxy-5-phenyl-2H-benzodiazepin-2-one (5.1.33), which upon hydrolysis using an alcoholic solution of potassium hydroxide forms a dipotassium salt (5.1.34), chlorazepate [30-32]. 

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