Oxazoles trifluoromethyl

A large variety of newer poly(ether imide)s has been described. Included among these are perfluorinated polymers (96), poly(ester ether imide)s (97), poly(ether imide)s derived from A/,Ar-diamino-l,4,5,8-naphthalenetetracarboxyHcbisimide (98), and poly(arylene ether imide ketone)s (99). In addition, many other heterocyHc groups have been introduced into polyether systems, eg, poly(pyrazole ether)s (100) and poly(aryl ether phenylquinoxaLine)s (101) poly(aryl ether oxazole)s with trifluoromethyl groups (102) and polyethers with other heterolinkages, eg, poly(arylether azine)s (103). 

Oxazol-5(2H)-one, 2-benzylidene-4-methyl-tautomerism, 6, 186 Oxazol-5(2ff)-one, 2-methylene-isomerization, 6, 226 Oxazol-5(2H)-one, 2-trifluoromethyl-acylation, 6, 201 Oxazol-5(4ff)-one, 4-allyl-thermal rearrangements, 6, 199 Oxazol-5(4H)-one, 4(arylmethylene)-Friedel-Crafts reactions, 6, 205 geometrical isomerism, 6, 185 Oxazol-5(4ff)-one, 4-benzylidene-2-phenyl-configuration, 6, 185 photorearrangement, 6, 201 Oxazol-5(4ff)-one, 4-benzyl-2-methyl-Friedel-Crafts reactions, 6, 205 Oxazol-5(4ff)-one, 4-methylene-in amino acid synthesis, 6, 203 Oxazol-5(4ff) -one. 2-trifluoromethyl-hydrolysis, 6, 206 Oxazolones... 

This formulation is supported by the proton resonance spectrum of the trifluoromethyl compound 101 which shows that it exists in the CH form shownd However, strong electron-withdrawing groups in the 4-position apparently lead to enolization, and compound 102, for example, gives an intense color with ferric chloride, - Other 4-acylated oxazol-5-ones are often formulated as 103 (see, e.g, reference 113). Tautomerism of the type illustrated by the equilibrium 104 103 has been discussed (see reference 115 for further references). 

Heating 5-(arylmethyloxy)-2-phenyl-4-(trifluoroniethyl)oxazoles 126 effects thermal rearrangement to 4-(arylmethyl)-2-phenyl-4-(trifluoromethyl)-5(4//)-oxa-zolones In some cases, the formation of 2-(arylmethyl)-2-phenyl-4-... 

SYNTHESIS OF (45, 55)-[(f -l,5-CYCLOOCTADIENE)- 2-(2-PHEN YL-5-METHYL, 5-DIHYDRO-OXAZOL-4-YL)-1,3-DIPHENYL-2-DIPHENYLPHOSPHINITE-PROPANE IRIDIUM(I)]-TETRAKIS[3,5-BIS(TRIFLUOROMETHYL)PHENYL]BORATE... 

Peiitenoic Acid 2-Benzoylamino-3-methyl-2-trifluoromethyl- EI0b2, 211 f. (4,5-H, — 1.3-oxazol-Der. f h20)... 

Hcptadicnoic Acid 2-Benzoylaini-no-5-methyl-2-trifluoromethyl-E10b2. 212 (4,5-H2 —1,3-oxazol-Der. + H,0)... 

Various other [3 + 2] cycloadditions, affording chiral, anellated C6o derivatives with stereogenic centers in the addends are reported in literature. The products were generally obtained as racemates and resulted from reaction of buckminsterfullerene with species like 2,3-disubstituted 2//-azirincs (via nitrile ylides [under direct irradiation] or via 2-azaallenyl radical cations [sensitization by photoinduced electron transfer]),365 1-substituted 5-diazopentane-1,4-diones (via cyclic carbonyl ylides),366 7-alkylidene-2,3-diazabicyclo[2.2.1] hept-2-ene (via a diradicaloid trimethylenemethane derivative),367 1-benzylpy-razolidine-3-ones in the presence of aldehydes (via pyrazolidinium ylides),368 2-trifluoromethyl-2,5-dihydro-l,3-oxazol-5-ones (via nitrile ylides),369 nitro-alkanes in the presence of triethylamine and trimethylsilyl chloride (via N-silyloxynitrones),370 or dv-HOCH2 CH=C H C H 2 OCO 2 H( in the presence of... 

Preparation of 2-[l-[4-[4-[[2-[(E)-2-[4-(trifluoromethyl)phenyl]ethenyl]-l,3-oxazol-4-yl]methoxy]phenyl]butyl]-lH-imidazol-2-yl]ethyl isopropylcarbamate... 

Photolytic (68CB302) or rhodium-catalyzed decomposition of alkyl 3,3,3-trifluoro-2-diazopropionates gives carbenes and carbene complexes, respectively, which exhibit an enormous synthetic potential. [3 + 2] cycloaddition reactions have been performed, e.g., with nitriles to give 4-trifluoromethyl-substituted oxazoles [90JOC3383 9IJFC(52)149]... 

With certain 4,4-bis(trifluoromethyl)-3-aza-l-oxabutadienes this transformation can be achieved on heating with metals (91CZ253), especially zinc (89CHE1418) or with zinc/ultrasound (91CZ253). The fluorine atom at C—5 can be readily replaced by various nucleophiles (88S194). Via this route, 4-trifluoromethyl-l,3-oxazoles, -1,3-thiazoles, and -imidazoles can be introduced into many compounds of biological interest (Scheme 85). 

A wide variety of a-trifluoromethyl-substituted amino acids are now available from the reaction of 5-fluoro-4-trifluoromethyl-l,3-oxazoles with allylic alcohols and benzyl alcohols. The reaction sequence involves a low-temperature Claisen rearrangement or a radical 1,3-benzyl shift from oxygen to carbon, respectively [88AG(E)848 89S850] (Scheme 86). 

Trifluoromethyl-l, 3-oxazoles are formed on heating 2-trifluoromethyl-2-acyl-2//-oxazol-5-ones (71CB1408) as well as 3-trifluoromethyl-3-alkox-ycarbonyl-2,2,2-trimethoxy-5-phenyl-2,3-dihydro-l,4,2-oxazaphospholes (89CZ243). Both reaction sequences include a thermally induced [3 + 2] cycloreversion reaction and a 1,5-electrocyclization of the conjugated 1,3-dipolar species initially formed (Scheme 93). 

Bis(trifluoromethyl)oxazol-5(2//)-ones are carbonyl-group protected, carboxyl-group activated, a-oxoacid derivatives that undergo reaction with benzene-1,2-diamine to yield quinoxa-lin-2(1 7)-one or its 3-alkyl- or 3-aryl-substituted derivatives. ... 

Benzene-l,2-diamine (5 mmol) in ElOAc (20 mL) was reacted with a 4-substituted 2,2-bis(trifluoromethyl)-oxazol-5(2//)-one (5 mmol). The reaction was catalyzed by few drops of glacial HOAc. Crystallization began after a short time, and the filtered products were recrystallized from MeOH. 

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