Gabriel s synthesis

The Gabriel s synthesis is also applicable when a polysubstituted thiazole is required (381, 550). Thus 2,4,5-trisubstituted thiazoles are obtained by treating the corresponding a-acylaminoketones with phosphorus pentasulfide for a few minutes at 100°C (550) or at higher temperature for heavier substituents (381). (Table 11-31). 

TABLE 11-31. THIAZOLES FROM -ACYLAMINOKETONES AND PHOSPHORUS PENTASULFIDE (Gabriel s synthesis)... 

The Gabriel s synthesis has been further extended to alkoxythiazoles. Thus 2-alkoxy (or aryloxymethyl) 5-methyl (or phenyl) thiazoles (200) were prepared by refluxing the corresponding acylaminoketone (199) in dry pr3ridine in the presence of P2S5 (Scheme 105) (409). 

Pteridine, 4-imino-1 -methyl-1,4-dihydro-basicity, 3, 270 Pteridine, 7-methoxy-synthesis, 3, 297 Pteridine, 2-methyl- H NMR, 3, 285 reactions, 3, 288 structure, 3, 266 Pteridine, 4-methyl-Gabriel s synthesis, 3, 309 H NMR, 3, 285 reactions, 3, 288 structure, 3, 266 Pteridine, 6-methyl-bromination, 3, 301 structure, 3, 266 synthesis, 3, 312 Pteridine, 7-methyl-aldol-type condensation, 3, 302 bromination, 3, 301 H NMR, 3, 285 structure, 3, 266 synthesis, 3, 312 Pteridine, 2-methylamino-solubility, 3, 271 Pteridine, 2-methyl-3,4-dihydro-striicture, 3, 279 Pteridine, 6-methyl-3,4-dihydro-structure, 3, 279... 

Gabriel s synthesis org chem A synthesis of primary amines by the hydrolysis of n-alkylphthallmldes the latter are obtained from potassium phthalimide and alkyl halides. ga-bre-alz, sin-tha-sas ... 

Fischer and Suzuki soon afterwards showed that Neuberg and Mayer s stone cystine contained tyrosine, and that its different behaviour to protein cystine was due to the presence of this compound. Rothera also could find no difference between stone cystine and protein cystine, and further, Gabriel s synthesis of isocysteine or a-thio-/8-aminopropionic acid and isocystine, which had quite different properties to cystine, though the two were much alike in many of their reactions, proved that stone cystine and protein cystine must be identical substances. Finally, it has been shown by Friedmann that a-thiolactic acid, ammonia PT. I. 4... 

Non-functionalized A2-thiazolines (328) are obtained by the classical Gabriel s synthesis which condenses a thioamide (326) with 1,2-dibromoalkanes (327 Scheme 215) (1890CB157). When an N-arylthioamide is employed, the product (329) is a 3-arylthiazolinium salt. This constitutes the only route to these salts with an aryl group substituted on the nitrogen atom. 

In Gabriel s synthesis of primary amines, potassium phthalimide is reacted with an alkyl halide and the resulting A-alkylphthalimide is hydrolysed to release the amine and phthalic acid (Scheme 5.12). This route is also used in the synthesis of amino acids. 

Gabriel, S. Synthesis of primary amines from the corresponding alkyl halides. Ber. 1887, 20, 2224-2236. 

Primary amines and their substitution-products, such as bromoethylamine, CH2BrCH2NH2, can be prepared by Gabriel s synthesis (558). 

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