Mercaptoacetal

The acetylation of d-tartaric acid with acetic anhydride has been effected by means of sulfuric acid 2 3 or hydrogen chloride.4 

1 Department of Chemistry, State University of Iowa, Iowa City, Iowa. 

Submitted by William E. Parham and Hans Wynberg.1 Checked by Max Tishler and George Purdue. 

1 -Tetraethoxyethyl polysuljide. (Note 1.) In a 5-1. round-bottomed flask, equipped with a stirrer, a reflux condenser, and an addition funnel, 540 g. (2.25 moles) of sodium sulfide enneahydrate (Note 2) is dissolved in 2.7 1. of boiling 95% ethanol. Sulfur (144 g., 4.5 gram atoms) is added, and the 

These directions have been used equally successfully with twice, one-third, and one-fifth the amounts specified. The reaction of chloro- or bromoacetal with sodium disulfide results in the formation of a considerable quantity of the corresponding monosulfide which is not subsequently reduced to mercaptan. Polysulfides are, however, easily reduced to mercaptans. 1,1,11 -Tetramethoxyethyl poly sulfide has been prepared from commercially available dimethyl chloroacetal in a similar fashion. A 10-hour heating period and the addition of 5 g. of potassium iodide per 100 g. of acetal are recommended in the latter preparation. 

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On the other hand, 4-amino-5-carbethoxy-2-methylthiothiazole (260) was obtained by condensing methyl-N-cyanoiminodithiocarbamic esaer (259) with ethyl-a-mercaptoacetate (258) in foramidine in the presence of triethylamine (Scheme 133) (564). 

A few isothiazoles, 2,1-benzisothiazoles and monocyclic sultams have been prepared by methods involving formation of the 4,5-bond. Thus, condensation of a-cyanooximes (179) with ethyl mercaptoacetate or related compounds gives a compound (180) which cyclizes... 

Elemental and inorganic compounds Manganese cyclopenta-dienyl tricarbonyl as Mn Manganese methyl-pentadienyl tricarbonyl Manganese tetroxide Man-made mineral fibre Marble, see Calcium carbonate Mercaptoacetic acid, see Thioglycolic acid Mequinol (INN)... 

Cyclocondensation of 3-cyano-2-methylthio-4//-pyrido[l, 2-u]pyrimidin-4-ones and ethyl mercaptoacetate in boiling EtOH in the presence of NaOEt afforded 4//-pyrido[l,2-u]thieno[2,3-r/ pyrimidin-4-ones 210 (00HC571). 2-Methylthio-4-oxo-4//-pyrido[l,2-u]pyrimidine-3-carboxylates 211 and mercaptoacetates afforded tricyclic derivatives 212 (93MIP1). Cyclocondensation of 2-methylthio-4-oxo-4//-pyrido[l, 2-u]pyrimidin-3-car-bonitriles 213 with H2NNH2 H2O and with guanidine HCl afforded tricyclic derivatives 214 and 215, respectively (96FES781). 

In another series of experiments, a novel approach to the determination of nucleotide sequence was adopted by A. S. Jones, Stacey, and their co-workers. For example, when calf thymus DNA was treated with mercaptoacetic acid in the presence of zinc chloride and anhydrous sodium sulfate, it yielded aldehydo-apurinic acid bis(carboxymethyl) dithioacetal. When degraded with dilute alkali, this afforded dialyzable fragments, which were separated into at least 20 components. Some were identified, including mono-, di-, and tri-nucleotides, thereby revealing that DNA contain regions of at least three linked pyrimidine nucleotides. The same procedure was applied to the DNA isolated from M. phlei ... 

The rapid synthesis of 4-thiazolidinones by the MCR of an amine, aldehyde and mercaptoacetic acid has been developed under microwave-assisted conditions [73-75]. Irradiation of the three components in ethanol at 120 °C in the presence of molecular sieves [73] or in toluene at reflux under atmospheric conditions [74] in a single-mode microwave synthesizer gave the... 

The one-pot synthesis of thiazolo[3,4-a]benzimidazoles has been reported using a microwave-assisted condensation-cyclization (see Scheme 17) of a substituted 1,2-diamine, substituted benzaldehyde and mercaptoacetic acid [74]. Heating the mixture at reflux for 12 min using a single-mode microwave reactor for the most part gave the fused benzimidazoles in improved yield and dramatically shorter times, when compared to classical conditions of heating at reflux in benzene for 24-48 h (Scheme 29). 

A small library of thiazolidinones 138 has been prepared mixing directly a primary amine (as the HCl salt), an aldehyde and mercaptoacetic acid in EtOH in the presence of Hiinig s base and molecular sieves (120 °C for 30 min) [88]. Working with a chiral amine, a 1 2 mixture of diastereoisomers was obtained (Scheme 49). 

As discussed in section 2, the alkyltin component of organotin compounds is relatively stable to environmental degradation processes such as hydrolysis, compared with the association with the relative ligand (such as an isooctyl mercaptoacetate group). Thus, in water, most of the derivatives are reported to dissociate to the constituent alkyltin (usually as the chloride or the oxide) and the relevant anion (KemI, 2000). 

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