Sulfonic acids, 2-amino synthesis

Thiazoles, vinyl-radical polymerization, 6, 278 Thiazole-5-sulfonic acid, 2-amino-synthesis, 6, 255-256 Thiazole-2-sulfonic acids reactions, 5, 104 6, 291 Thiazole-5-sulfonic acids synthesis, 6, 255 Thiazole-5-thione, 2-phenyl-tautomerism, 6, 249 Thiazolethiones reactivity, 6, 250 Thi azole-2-thiones reactions, 5, 102 tautomerism, 5, 367 Thiazolidine, 2-alkyl-occurrence, 6, 327 Thiazolidine, 2-arylimino-X-ray analysis, 6, 238 Thiazolidine, 4-imino-mesoionic didehydro derivative nomenclature, 1, 34 nomenclature, 1, 34... 

In another variation of a type E synthesis, thioamides or thioureas condense with /V,/V-dimcthylacylamide dimethyl acetal to give imino compounds which react with amino-transfer reagents like hydroxylamine-O-sulfonic acid and mesitylsulfonyloxyamine (MSH) to give 3,5-substituted-l,2,4-thiadiazoles in excellent yields <1996CHEC-II(4)307>. There have been no new reports of type E syntheses since the publication of CHEC-II(1996). 

Most immobilization methods require modification of the ligands for anchoring to the support by introducing functional groups such as vinyl, trialkoxysilyl, sulfonic acid, and amino groups. The consequence is often a more elaborate synthesis of the ligand, which adds to the costs of an immobilized catalyst. However, two interesting approaches were developed in recent years, when unmodi-... 

For the analytical characterization of sulfated tyrosine peptides, spectroscopic methods as well as amino acid analysis and, more recently, mass spectrometry are employed. In Table 2 the spectroscopic data of tyrosine 0-sulfate are compared to those of the related sulfonic acid derivatives as possible byproducts in the chemical sulfation of the tyrosine or tyrosine peptides.[361 In the course of the synthesis of tyrosine 0-sulfate peptides and, particularly in the final deprotection step, desulfation may occur which limits the characterization of the final compounds in terms of quantitative identification of the tyrosine 0-sulfate. This is achieved by amino acid analyses of basic hydrolysates of the sulfated tyrosine peptides or preferably by analyses of the enzymatic hydrolysates with aminopeptidase M or leucine-aminopeptidase. 

The synthesis of a-sulfonamidopeptides, i.e. the direct substitution of the carboxylic group of a-amino acids with a sulfonic acid group, remains an elusive goal because, unlike the a-amino acids, a-aminoalkyl sulfonic acids are unstable in solution and decompose to give an aldehyde, sulfur dioxide, and ammonia (Scheme 23).f105 ... 

Introducing the Tau residue into a peptide according to the first approach demands protection of the amino group, usually in the form of a Z-derivative and turning the sulfonic acid into sulfonyl chloride. Synthesis of (j-su Ifonamidopeptides via an iterative process, both in solution and in the solid phase, has been described.11201 Chiral methylene sulfinamide peptides can be synthesized both in solution and in the solid phase using the sulfonyl chlorides derived from enantiomerically pure 2-substituted taurines under mild coupling conditions (DMAP catalysis and excess methyl trimethylsilyl dimethylketene acetal as a proton trap).11261... 

The synthesis of the 1 1 complex 8 is an example of [10] demethylative chroma-tion. It is prepared by diazotization of 5-amino-2-chlorohydroquinone dimethyl ether and coupling onto 1-hydroxynaphthalene-5-sulfonic acid. The reaction product and Cr203 in formic acid are heated in an autoclave at 130 °C. The chromium complex 8 [80004-31-5] is obtained as a black powder that gives grayish blue dyeings on wool and leather. 

In the stepwise synthesis of the unsymmetrical complex dye 13 [ 70236-60-1] [10], the azo dye made from diazotized l-amino-2-hydroxy-5-nitrobenzene and 1-phenyl-3-methyl-5-pyrazolone and the 1 1 chromium complex obtained from 6-nitro-l-diazo-2-hydroxynaphthalene-4-sulfonic acid and 2-naphthol are heated together at 80 °C for 5 h. The adduct is salted out with NaCl. A black powder is obtained that dyes wool and leather in dark brown shades. The resulting colors are fast, particularly on shrink-resistant wool. 

In the synthesis of the disulfonated 1 2 chromium complex dye 16 [82269-28-1] [28], a mixture of the azo compound made from diazotized 2-amino-1,4-dichlorobenzene-5-sulfonic acid and salicylaldehyde is heated to 50 °C with... 

In the synthesis of the 1 1 cobalt complex 17 by the nitrite method, a mixture of CoS04-7 H20 and NaN02 in water and the dye formed by acid coupling of diazotized 2-amino-4,6-dinitrophenol with 2-phenylaminonaphthalene-4 -sulfonic acid is subjected to dropwise addition of dimethylformamide. Metallization commences immediately and is complete within 2 h. The 1 1 cobalt complex 17 is precipitated by addition of NaCl and isolated. It is a suitable intermediate for producing unsymmetrical 1 2 cobalt complex dyes such as 18. 

In the synthesis of the symmetrical 1 2 cobalt azomethine complex 19 [41043-60-1] [31], a mixture of 2-amino-6-nitrophenol-4-sulfonic acid and salicylaldehyde is heated to boiling in sodium acetate solution. The suspension is cooled and mixed first with CoCl2-6H20 and then with 30% H202. The resulting solution is salted out with NaCl and KC1. The dye yields exceptionally lightfast yellow colors on wool and polyamides. 

Most reported phthalocyanine derivatives (sulfo-, nitro-, amino-, triphenylmethyl-, polymeric, etc.) are copper complexes, although at present the synthetic chemistry of other d- and /-metal Pc derivatives is being rapidly developed (Examples 30-36) [5,6,116-118]. Some of them (in particular, copper phthalocyanine sulfonic acids) are of industrial interest because of their usefulness as dyes. Phthalocyanine sulfonic acids themselves are prepared both by urea synthesis from sulfonated phthalic anhydride and by the sulfonation of the phthalocyanine [6], Some substituted metal phthalocyanines can be obtained by chemical or electrochemical reduction [118e]. Among a number of reported peculiarities of substituted phthalocyanines, the existence of three electronic isomers for magnesium derivative PcMn was recently confirmed [118f]. 

The synthesis of 3-alkyl-substituted 1,2-thiazetidine 1,1-dioxides starts by transformation of the amino acids L-Val, L-Leu, L-Ile, and L-Phe into amino alcohols. These ate converted via the bromides to the corresponding thiols 161. Immediate oxidative chlorination affords either sulfonyl chloride hydrochlorides or sulfonic acids 162 which are transformed into the parent /3-sultams 163 <2004HCA90>. Similarly, L-cystine derivatives 164 have also been transformed into the parent /3-sultams 165 by oxidative chlorination followed by cyclization (Scheme 50) C1997LA1261, 2004HCA90>. 

Further acid-catalyzed reactions include the use of />-toluene sulfonic acid-DMF in a cyclization of the protected amino acid 17 (DMF = dimethylformamide Scheme 15) <20040L4941>. This was the key step in the stereoselective synthesis of 5-hydroxypipecolic acid. A similar acid-catalyzed ring closure of a hemiacetal yielded the fused piperidine 18 <2004JOC1872> (Equation 32). The indolizidine alkaloid can be accessed by a Barton-Ester method utilizing a polyphosphoric acid (PPA) cyclization (Scheme 16) <1994T19157>. 

Of similar nature are chiral halogenations using auxiliary groups. Typical examples are the conversion of esters to enantiomerically pure halohydrins (precursors to chiral epoxides) using camphor-10-sulfonic acid derivatives583 and the chiral synthesis of a-amino acid synthons via diastereoselective bromination of TV-acyl oxazolidone derivatives584. 

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