Tartaric acid reaction conditions

The corrosion of tin by nitric acid and its inhibition by n-alkylamines has been reportedThe action of perchloric acid on tin has been studied " and sulphuric acid corrosion inhibition by aniline, pyridine and their derivatives as well as sulphones, sulphoxides and sulphides described. Attack of tin by oxalic, citric and tartaric acids was found to be under the anodic control of the Sn salts in solution in oxygen free conditions . In a study of tin contaminated by up to 1200 ppm Sb, it was demonstrated that the modified surface chemistry catalysed the hydrogen evolution reaction in deaerated citric acid solution. 

The results obtained appeared quite promising, but the real sensation was the detection of pyruvate, the salt of 2-oxopropanoic acid (pyruvic acid), which is one of the most important substances in contemporary metabolism. Pyruvic acid was first obtained in 1835 by Berzelius from dry distillation of tartaric acid. The labile pyruvate was detected in a reaction mixture containing pure FeS, 1-nonanethiol and formic acid, using simulated hydrothermal conditions (523 K, 200 MPa). The pyruvate yield, 0.7%, was certainly not overwhelming, but still remarkable under the extreme conditions used, and its formation supports Wachtershauser s theory. Cody concludes from these results that life first evolved in a metabolic system prior to the development of replication processes. 

The enantioselective hydrogenation of prochiral substances bearing an activated group, such as an ester, an acid or an amide, is often an important step in the industrial synthesis of fine and pharmaceutical products. In addition to the hydrogenation of /5-ketoesters into optically pure products with Raney nickel modified by tartaric acid [117], the asymmetric reduction of a-ketoesters on heterogeneous platinum catalysts modified by cinchona alkaloids (cinchonidine and cinchonine) was reported for the first time by Orito and coworkers [118-121]. Asymmetric catalysis on solid surfaces remains a very important research area for a better mechanistic understanding of the interaction between the substrate, the modifier and the catalyst [122-125], although excellent results in terms of enantiomeric excesses (up to 97%) have been obtained in the reduction of ethyl pyruvate under optimum reaction conditions with these Pt/cinchona systems [126-128],... 

Surface modification of skeletal nickel with tartaric acid produced catalysts capable of enantiose-lective hydrogenation [85-89], The modification was carried out after the formation of the skeletal nickel catalyst and involved adsorption of tartaric acid on the surface of the nickel. Reaction conditions strongly influenced the enantioselectivity of the catalyst. Both Ni° and Ni2+ have been detected on the modified surface [89]. This technique has already been expanded to other modified skeletal catalysts for example, modification with oxazaborolidine compounds for reduction of ketones to chiral alcohols [90],... 

The initial medicinal chemistry route to the azabicyclo[3.3.0]octane-3-carboxylic acid produced the azabicyclo system in a diastereoselective but racemic manner, and required a classical resolution to achieve enantioenriched material (Teetz et al., 1984a, b 1988). Reaction of (R)-methyl 2-acetamido-3-chloropropanoate (43) and 1-cyclopentenylpyrrolidine (44) in DMF followed by an aqueous acidic work-up provided racemic keto ester 45 in 84% yield (Scheme 10.11). Cyclization of 45 in refluxing aqueous hydrochloric acid provided the bicyclic imine, which was immediately reduced under acidic hydrogenation conditions. The desired cis-endo product 46 was obtained upon recrystaUization. The acid was protected as the benzyl ester using thionyl chloride and benzyl alcohol, providing subunit 47 as the racemate. Resolution of 47 was accomplished by crystallization with benzyloxy-carbonyl-L-phenylalanine or L-dibenzoyl-tartaric acid. 

Fig. 6. Effect of modifying temperature on EDA with the following modifying reagent and conditions ( ) (+)-erythro-2-methyltartaric acid, pH 5.0 5.2, 0°C (O) (S.S)-tartaric acid, pH 5.0-5.2, 0°C (A) ( + )-2-methyl glutamic acid, pH 5.0, 0°C (O) (S)-valine, isoelectric point, 0 C ( ) (S)-glutamic acid, pH 5.2, 0 C. Reaction conditions MAA (neat), 60"C, 80 100 kg/cm2.

The 1,3-dioxolane and 1,3-dioxane systems are stable to an extremely wide range of reaction procedures provided that an acidic medium is avoided. Deprotection is effected under a wide variety of mild acid conditions such as, for example, aqueous tartaric acid,134 perchloric acid,135 or moist silica gel either alone or in the presence of oxalic or sulphuric acids.136 The mild oxidative cleavage reaction with triphenylmethyl tetrafluoroborate in dichloromethane is... 

The second-generation synthesis of (S,S)-TaDiAS 1 is summarized in Scheme 6.1 [16], This process requires only common and inexpensive reagents under operationally simple reaction conditions. When using the first-generation synthesis (a five-step process from diethyl tartrate) [4a] or the second-generation synthesis (a four-step process from tartaric acid), a variety of catalysts with versatility on the acetal moieties (R1 and R2) and aromatic parts (Ar) were synthesized (over 100 derivatives) [18]. A large-scale reaction (>20g) can also be performed with the same efficiency. 

The 11-membered chiral tris-sulfide 67 was obtained in a high yield of 80% by Kellogg et al. [16] from the reaction of the D-tartaric acid derivative 66 with 3-thiapentanedithiol under dilution conditions in DMF. 

Preparative Methods to a solution of (R,R)- or (5,5)-mono-(2,6-diisopropoxybenzoyl)tartaric acid (74 mg, 0.2 mmol) in dry dichloromethane or propionitrile (1 mL) is added BH3 THF (0.189 mL of 1.06 M solution in THE, 0.2 mmol) at 0 °C under an argon atmosphere. The reaction mixture is stirred for 1 h at 0 °C to produce the chiral acyloxyborane. Only 2 equiv of hydrogen gas should evolve under these reaction conditions (0°C). See also Euruta. ... 

Asymmetric Diels-Alder Reaction of Unsaturated Carboxylic Acids. A chiral acyloxyborane (CAB) complex (1) prepared from mono(2,6-dimethoxybenzoyl)tartaric acid and 1 equiv of borane is an excellent catalyst for the Diels-Alder reaction of a,p-unsaturated carboxylic acids and dienes. In the CAB-catalyzed Diels-Alder reaction, adducts are formed in a highly diastereo- and enantioselective manner under mild reaction conditions (eq 2). The reaction is catalytic 10 mol % of catalyst is sufficient for efficient conversion, and the chiral auxiliary can be recovered and reused. 

CAB 2, R = H, derived from monoacyloxytartaric acid and diborane is also an excellent catalyst (20 mol %) for the Mukaiyama condensation of simple enol silyl ethers of achiral ketones with various aldehydes. The reactivity of aldol-type reactions can, furthermore, be improved, without reducing the enantioselectivity, by use of 10-20 mol % of 2, R = 3,5-(CF3)2C6H3, prepared from 3,5-bis(trifluoromethyl)phenyl-boronic acid and a chiral tartaric acid derivative. The enantioselectivity could also be improved, without reducing the chemical yield, by using 20 mol % 2, R = o-PhOCgH4, prepared from o-phenoxyphenylboronic acid and chiral tartaric acid derivative. The CAB 2-catalyzed aldol process enables the formation of adducts in a highly diastereo- and enantioselective manner (up to 99 % ee) under mild reaction conditions [47a,c]. These reactions are catalytic, and the chiral source is recoverable and re-usable (Eq. 62). 

Intramolecular phosphonate-based olefination has been used to construct five-membered rings in a number of syntheses for example in a novel approach to [3.3.0] fused pyrazolidinones (244) (Scheme 35), a totally synthetic class of antibacterial agents. 44 new, convergent synthesis of the fungal metabolite and useful synthetic intermediate (+)-terrein (248) has been reported. 45 The method is based on two phosphonate olefination steps. The diphosphonate (245), obtained from L-tartaric acid, gives, on treatment with base, a mixture of the required phosphonate (24 6) and the diphosphonate (247). However, under appropriate conditions (246) is the major product and can be converted into (+)-terrein by reaction with acetaldehyde (Scheme 36). Olefination of the ketone (249) with dimethyl diazomethylphosphonate (250) provides, via carbene insertion, the cyclopentene (251) and hence a new route to (-)-frontalin (252) (Scheme 37).146... 

Scheme 12.32 Crignard reactions at carbon C9 with complete inversion and complete retention. Reagents and conditions (a) SOCI2 (b) MsCI, Et3N, toluene, rt (c) 1. tartaric acid, H20, reflux, 0.5 h 2. SOCI2 (d) PhMgBr (1.4 equiv), Et20, toluene, reflux, 4 h.

Iron(IlI) does not interfere in the determination of Mo since, under the reaction conditions, it is reduced to Fe(II). Tungsten is masked with citric or tartaric acid, and titanium is masked with fluoride. Larger quantities of Re, U, V, Co, Cu, and Bi interfere. 

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