Thiazoles 2-acylamino

Thiazole, 2-acetylamino-4-methyl-alkylation, 6, 256 Thiazole, 2-acylamino-4-hydroxy-synthesis, 6, 297 Thiazole, 5-alkoxy-cleavage, 6, 289 synthesis, 6, 302 Thiazole, 2-alkyl-A7-alkylation, 6, 253 hydrogen exchange, 6, 276 methylation, 6, 253 quatemization, 6, 253-254 reactions, S, 88 Thiazole, 4-alkyl-A7-alkylation, 6, 253 methylation, 6, 253 quatemization, 6, 253-254 Thiazole, 5-alkyl-A7-alkylation, 6, 253 methylation, 6, 253 Thiazole, 2-alkylamino-tautomerism, 6, 248 Thiazole, 4-alkyl-2,5-dimethyl-quatemization, 6, 253-254 Thiazole, 2-alkylthio-reactions, S, 103 rearrangement, 5, 103 6, 291 Thiazole, 3-allyl-4-hydroxy-2-imino-synthesis, 6, 297 Thiazole, 2-allyloxy-rearrangement, 6, 289 Thiazole, 2-amino-diazo coupling, 6, 257 nitration, 6, 255... 

Thieno[2,3 -h]selenophenes lithiation, 4, 950 Thienospirans synthesis, 4, 760 Thieno[3,4-c][l,2,5]thiadiazoles cycloaddition reactions, 6, 534 reactions, 6, 1036 synthesis, 6, 1042, 1044 Thieno[2,3-d]thiazole, 2-acylamino-synthesis, 6, 1010 Thieno[2,3-d]thiazoles synthesis, 5, 116 6, 988, 994 Thieno[3,2-d]thiazoles synthesis, 5, 135 6, 1015 Thieno[3,4-d]thiazolidine-2-thione, perhydro-... 

The reaction of phosphorus pentasulfide with a-acylamino carbonyl compounds of type Ilia also yields thiazoles. Even more commonly, a mercaptoketone is condensed with a nitrile of type IVa or a-mercaptoacids or their esters with Schiff bases. This ring closure is limited to the thiazolidines. In the Va ring-closure type, /3-mercaptoalkylamines serve as the principal starting materials, and ethylformate is the reactant that supplies the carbon at the 2-position of the ring. These syntheses constitute the most important route for the preparation of many thiazolidines and 2-thiazohnes. In the Vb t3fpe of synthesis, one of the reactant supplies only the carbon at the 5-position of the resultant thiazole. Then in these latter years new modern synthetic methods of thiazole ring have been developed (see Section 7 also Refs. 515, 758, 807, 812, 822). 

A general synthetic route to meso-ionic iV-acyl-l,3-thiazol-5-imines (108, R = Ph, = Me, R = Me or Ph, R = COPh) is provided by treatment of thiobenzamidoaminoacetonitriles, Ph-CS-NMe-CHR-CN, first with benzoyl chloride and then with aqueous alkali. Alternatively, the thiobenzamidoaminoacetonitriles and hydrogen chloride give the corresponding salts, which with benzoyl chloride and aqueous alkali give -acyl l,3-thiazol-5-imines Derivatives (108, R = SMe) have been obtained by treating 5-acylamino-4-thiazoline-2-thiones with methyl iodide and aqueous alkali. ... 

Synthesis of imidazoles, oxazoles and thiazoles from acylamino ketones 569... 

Acylamino ketones also provide a convenient synthesis of thiazoles on treatment with phosphorus pentasulfide (Gabriels method). Substituents are usually restricted to alkyl, aryl, and alkoxy derivatives. Thus, the -acylamino ketone 234 with P4S10 gave the thiazole 240. Lawessons reagent (LR) can be effectively used as the source of sulfur in these cyclizations (e.g., Scheme 116) <1996JME957, 2006TL2361, CHEC-III(4.06.9.1.3)682>. 

Aminothiophenol is cyclized by reaction with prop-2-ynyltriphenylphos-phonium bromide, but some 2-substituted anilines give the phosphonium salt (a possible intermediate in the thiophenol reaction) which may be cyclized separately (see Chapter 16, Section I.S) [2736]. Reaction of thiophenols with the lactonic 2-oxazolin-S-ones can give any one of three products in acetic acid-sodium acetate, cyclization to the thiazole occurs while in some other solvents, acylamino and acylthio products are formed, and may be cyclized by acetic acid-sodium acetate [3088]. 

Cyclising dehydration of an a-acylamino-carbonyl-compound is particularly important for oxazoles, and can be adapted for thiazole or imidazole formation. 

Bei Verwendung von Acetanhydrid als Dehydratisierungsmittel fur a-Acylamino-thiocarbon-saure-amide wurden unter zusiitzlicher Acetylierung 5-Acetamino-l, 3-thiazole erhalten716. 

Zwitterionische /J-Acylamino-a-triphenylphosphaniono-dithiocarbonsaure-ester kondensieren im Sauren zu 5-Arylthio-4-triphenylphosphaniono- bzw. 5-Alkylthio-4-triphenyl-phosphaniono-l,3-thiazolen1845, z.B. zu 2-Ethylthio-5-phenyl-4-triphenylphosphaniono-1,3-thiazol-perchlorat (81%) ... 

Die S-Acyl-Gruppe in l-Acety]thio-2-(4-isopropyliden-5-oxo-4,5-dihydro-l,3-oxazol-2-yl)-2-(phenoxy-acetylamino)-ethen laBt sich hydrolytisch entfernen, so daB der gebildete Acylamino-thioacetaldehyd zum 1,3-Thiazol cyclisieren kann1216. Dasselbe Produkt wird durch Hydrolyse eines entsprechenden Disulfans unter S —S-Spaltung erhalten1216. 

Bci der Chlorierung von 5-Acylamino-2-mercapto-l, 3-thiazolen mit Chlor tritt das Chlor-Atom in 4-Position ein. Gleichzeitig wird die Mercapto-Gruppe chloriert, so daB nach Zugabe von Ammoniak 5-Acylamino-2-aminosulfonyl-4-chlor-l, 3-thiazole gebildet werden15" z.B. ... 

Wie fur Thiole allgemein iiblich, ergeben Mercapto-l,3-thiazole bei milder Oxidation zumeist entsprechende Disulfane (s.Bd. IV/la, S. 279). Durch Chlorierung sind aber aus 5-Acylamino-2-mereapto-l, 3-thiazolen auch 2-Sulfochloride zuganglich, die mit Ammoniak zu Sulfonamiden umgesetzt wurden1516 z. B. ... 

Warming an acylamino ketone with a stoichiometric amount phosphorus pentasulfide yields the corresponding thiazole product. The reaction was first discovered by Gabriel in 1910. ... 

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