Phase transfer catalysis tetrabutylammonium bromide

Alkylation of 2,4-disubstituted-5(477)-oxazolones can be conveniently performed via phase-transfer catalysis. For example, the substrate and an alkyl halide are dissolved in an organic solvent and stirred with an aqueous sodium carbonate solution containing tetrabutylammonium bromide as a phase-transfer catalyst. 4,4-(Diarylmethyl)-2-phenyl-5(4/f)-oxazolones can be prepared in one-step by dialkylation of 146 using magnesium methyl carbonate and the corresponding... 

Compound 98 was condensed with o-aminothiophenol, 2-aminoethanol, or cystamine in refluxing diphenyl ether through an intermolecular cyclization with the elimination of two molecules of water to give the polyfused derivatives 101-103, respectively. Also, the reactions of 98 with dimethylthiomethylenemalononitrile in boiling dimethylforma-mide (DMF) were studied. The dimethylthiomethylenemalononitrile was prepared via the reaction of malononitrile with CS2 with 2 equiv of methyl iodide in a one-pot reaction using liquid-liquid phase-transfer catalysis (PTC) technique (NaOH/dioxane/tetrabutylammonium bromide (TBAB)). The product of this reaction was identified as 8-cyano-9-imino-7-methylthio-6-oxo-3-phenyl-5,6,8,9-tetrahydro-77/-pyrano[3,2-/][l,2,4]-triazolo[3,4-A][l,3,4]thia-diazepine 104 (Scheme 10). 

The reaction of ethyl 2-phenyl-4//-furo[3,2-/>]pyrrole-5-carboxylate (94) with 2-nitrobenzyl-oromide afforded ethyl 4-(2-nitrobenzyl)-2-phenylfuro[3,2-6]pyrrole-5-carboxylate (269) under conditions of phase transfer catalysis by utilization of sodium carbonate and tetrabutylammonium bromide. This product (269) was hydrogenated using palladium-on-charcoal catalyst to give the amine (270), which cyclized in the presence of 2-hydroxypyridine to give 2-phenylfuro[2, 3 4,5]pyrrolo[2,l-c]benzo[l,4]diazepin-l 1-one (271) <92CCC1487>. 

The synthesis of some new substituted thieno[2,3-Z>]thiophenes (369)-(372) has been achieved <93BCJ201l> in a one-pot reaction employing solid-liquid phase transfer catalysis (PTC) conditions (K2C03, benzene, tetrabutylammonium bromide catalyst) and starting from acetylacetone, CS2, and a-chloro compounds in 1 1 2 molar ratio. The reaction of acetylacetone and CS2 with ethyl chloroacetate, chloroacetonitrile, 2-(chloroacetylamino)thiazole, or chloroacetanilide was carried out under PTC conditions by stirring the reactants reaction times and temperatures were optimized. The corresponding thieno[2,3-6]thiophenes (369)-(372) were obtained in excellent yields (51-93%). 

Fig. 9. Reaction steps involved in the synthesis of decyl sulfonate from decyl bromide and sodium sulfite using phase transfer catalysis. Q stands for tetrabutylammonium...

Anilines are converted into nitrosoarenes ArNO by the action of hydrogen peroxide in the presence of [Mo(0)(02)2(H20) (HMPA)] ", whereas catalysis of the reaction by titanium silicate and zeolites results in the formation of azoxybenzenes ArN (0)=NAr. Azo compounds ArN=NAr are formed in 42-99% yields by the phase-transfer assisted potassium permanganate oxidation of primary aromatic amines in aqueous benzene containing a little tetrabutylammonium bromide. The reaction of arylamines with chromyl chloride gives solid adducts which, on hydrolysis, yield mixtures of azo compounds, p-benzoquinone and p-benzoquinone anils 234. ... 

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