5-chloro-2,4-diphenyloxazole

Padwa and Cohen prepared a series of 2-aIkoxy-4,5-diphenyloxazoles 668 from 2-chloro-4,5-diphenyloxazole 667 and the corresponding sodium alkoxide (Scheme 1.184). These 2-aIkoxy-4,5-diphenyloxazoles 668 were substrates for the authors systematic investigations of the thermal and photochemical [3,3]-sigma-tropic rearrangements of suitably substituted oxazoles (see Section 1.4.5). 

Besides benzalanilines, also anils derived from heterocyclic aldehydes may be employed (Table VI), as, for example, in the reactions of 4,5-diphenyl-2-(p-tolyl)oxazole (58) with SchifFs bases from p-chloro-aniline and 3-formylpyridine and 2-formylthiophene, leading, respectively, to the /3-(3-pyridyl)-4-(4,5-diphenyloxazol-2-yl)styrene (59) 33 and the /S-(2-thienyI) analog (60).11... 

Neutral oxazolones and oxazolethiones are inert towards most electrophiles. 5(4//)-Oxazolones are reversibly protonated at the nitrogen atom. When the 2-oxazolone (194) is treated with sulfuric acid, 2-methyl-4,5-diphenyloxazole is produced (equation 31). 2(3/Z)-Oxazolones and benzoxazolones react with phosphoryl chloride to yield the corresponding 2-chloro-oxazoles and -benzoxazoles (equation 32). 

Further, Padwa and Battisti168 reported that 2,5-diphenyloxazole is also obtained in high yield (80%) by the irradiation of the invertomers (100 and 101) of V-chloro-[Pg.139]

A somewhat related rearrangement was described by Zaugg and DeNet.171 l-Benzoyl-2,2-dichloro-3-phenylaziridine rearranges thermally to give 4-chloro-2,5-diphenyloxazole in 81% yield. The exact mechanism of the reaction is not known but is believed to proceed through the intermediate 107.171... 

Binaphthalene)-2,2 -diylbis(diphenylphosphine-/cP)]trifluorome-thanesulfonato-/cO-silver Chloro( ) -cyclopentadienyl)[(47J( fra/js)-2,2-dimethylQ, Q ,Q, ei -tetraphenyl-1,3-dioxo-lane-4,5-di-methanolato(2-)-Ch , QV] titanium 2,2-dimethyl-Q, Q ,Q, Qr"-tetraphenyl- l,3-Dioxolane-4,5-dimethanolatotitanium diisopro-poxide chloro(cyclopentadienyl)bis[3- 0-( 1,2 5,6-di- O-isopro-pylidene-a -D-glucofuranosyl)]titanium 2,2 -Methylenebis-[(45,5/ )-4,5-dihydro-4,5-diphenyloxazole-/cT S] bis(trifluoro-methanesulfonato-/cO-zmc Aqua] 2,6-bis[(45)-4,5-dihydro-4-... 

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