Oxazoles, 2,5-dihydro-5-trifluoromethyl

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... 

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... 

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). 

Dihydro-5-methoxy-2,2-dimethyl-4 (iV-methyl-A -phenylamino)-5-trifluoromethyl-l,3-oxazole[i]... 

Transition metal compounds can be replaced by other substances, for example, by phosphites. Thus, 2-substituted 4-trifluoromethyl-5-fluoro-l,3-oxazole-2,4-dienes 9 were obtained by the reaction of 4,4-bis(trifluoromethyl)-N-acylimine 10 with trimethylphosphite (71CB1826, 74CB1448). The reaction occurs via the intermediate formation of 5-substituted 3,3-bis(trifluoromethyl)-2,2-dihydro-1,4,2-oxazaphos-pharol-4-ene 11 (Scheme 15). 

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See also in sourсe #XX -- [ , ]

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