4.5- diphenyl-2-methyloxazole

For example, reaction of propiophenone and benzonitrile with mercury(ll) tosylate affords 2,4-diphenyl-5-methyloxazole 196 (Scheme 1.52). Mechanistically, the authors proposed initial formation of a di(a-arylalkanoyl)Hg(ll) species 192 from reaction of the enol tautomer of propiophenone with mercury(II) tosylate. Reaction of 192 with benzonitrile generates 193, which collapses to the oxirane 194 with loss of mercury. Rearrangement of 194 and loss of... 

Treatment of 1,2,3-triazole-4,5-dicarboxylic acid (118) with acetic anhydride leads to 2-methyloxazole-4-carboxylic acid.181 The mechanism of the reaction is not yet clear, but it may be related to the thermal decomposition of l-benzoyl-4,5-diphenyl-l,2,3-triazole, which on heating above 250° gives 2,4,5-triphenyloxazole (29%), presumably through the acyliminocarbene intermediate 119.18S... 

Infrared spectra of 4-methyloxazole and 2,4-dimethyloxazole for the gaseous and liquid states, and of liquid 2-n-hexy 1-5-methyl oxazole, have been measured at room temperature between 4000 and 600 cm-1. A comparison with the spectra of oxazole and considerations of the rotational envelopes has allowed a plausible assignment of the absorption bands with reasonable success.261 Examination of the infrared spectra in the solid state of 2,4-dimethyl-, 2-methyl-4-phenyl-, and 2-methyl-4,5-diphenyl-oxazolcs, and various benzoxazoles shows regularities in the 1660-1500 cm-1 region. Absorption bands at 1660-1600 cm-1 and 1585-1500 cm-1 have been assigned to the vibrations arising from the heterocyclic ring system.262... 

Reactions of Oxazoles. The reaction of 4-phenyloxazole with di(acetoxy-methyl)acetylene gives the furan (531 R = CH2OAC) by extrusion of benzo-nitrile from the intermediate Diels-Alder adduct (530 R = CH20Ac). Similarly, 5-cyano-4-methyloxazole and hept-l-yne yield mainly the furan (532) and methyl cyanide a minor product, the 4-substituted isomer (533), arises from the alternative mode of addition of the acetylene. The sensitized photooxidation of 2,4-diphenyl-2-oxazolin-5-one (534) affords, inter alia, the coupled product (535). ... 

Wasserman and Prowse " condensed 312b with benzaldehyde to produce 2,5-diphenyl-4-methyloxazole iV-oxide 315 (Scheme 1.85). Treatment of 315 with POCI3 gave 4-(chloromethyl)-2,5-diphenyloxazole 316, a key starting material in their synthesis of ( )-pyrenolide C 317. 

Similarly, bromination of 4,5-diphenyl-2-methyloxazole 15 (Ri = CH3, R2 = R3 = CeHs) at —78° to —5°C afforded a mixture of cis/trans 2,5-dimethoxy-4,5-diphenyl-2-methyl-3-oxazoline 602 (Ri = CH3, R2 = R3 = CeHs) in 76% yield together with 13% of benzil, respectively. 

Irradiation of a methanolic solution of an oxazole at —78°C in the presence of O2 and rose bengal produced a 2,5-disubstituted 5-hydroperoxy-4-methoxy-4,5-dihydrooxazole 709 (Scheme 1.197). Here again, the oxazole substitution pattern determined the product distribution. For example, 4,5-diphenyl-2-methyloxazole 231a produced only N, iV-dibenzoyl acetamide 706 (Ri = CH3, R2 = R3 = CeHs). On the other hand, 4-methyl-2-phenyloxazole 701a gave 709 (Ri = CgHs, R2 = CH3, R3 = H), which decomposed on warming to room temperature to yield... 

SmithKline chemists adapted singlet oxygen oxidation methodology to prepare ( )-methyl (5S), (6S)-oxido-7-hydroxyheptanoate 730 (n=l), a key fragment of leukotrienes A-E (Scheme 1.201). 4,5-Diphenyl-2-methyloxazole 231a was converted to the allylic alcohol 727 in five or six straightforward steps. 

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