Phenyl benzoxazoles

Reagents. 2- ( 2-Hydroxy phenyl) benzoxazole solution. Dissolve 1.0 g of the solid reagent in 1 L of 95 per cent ethanol. 

Glorius and colleagues [304] described a useful Cu -catalyzed preparation of 2-phenyl benzoxazoles 6/4-97 and related compounds from 1,2-dihaloaromatic substrates 6/4-95 and benzamide 6/4-96 (Scheme 6/4.23). 

Al-Soufi W, Grellmann KH, Nickel B (1991) Keto-enol tautomerization of 2-(2 -hydroxy-phenyl)benzoxazole and 2-(2 -hydroxy-4 -methylphenyl) benzoxazole in the triplet state hydrogen tunneling and isotope effects. 1. Transient absorption kinetics. J Phys Chem 95 10503-10509... 

Sun [68] synthesized the 2-(4-(lH-phenanthro [9, 10-d]-imidazol-2-yl)phenyl)-benzoxazole (xL) and 2-(4-(4,5-diphenyl-lH-imidazol-2-yl)phenyl)-benzoxazole (xLi) nitrogen containing heterocyclic chromophores by using a three-component, one pot reaction under microwave irradiation. 

Similar attack of methanol on the presumed oxaziridine intermediate in the photolysis of C,N-diphenylnitrone led to the formation of 2- and 4-methoxyazoben-zenes."" The reaction converting dibenz[b,f] [l,4]oxazepine 60 to 2-(2-hydroxy-phenyl)benzoxazole 62 seems better explained by a nucleophilic substitution on protonated 61 than by the electrophilic process suggested by the authors. ... 

Gross and coworkers129 also studied the unimolecular dissociation of protonated acy-lanilines, viz. A-[2-(benzoyloxy)phenyl]benzamides formed via both fast-atom bombardment (FAB) and electrospray ionization (ESI). They found that cyclization occurs upon the loss of a molecule of benzoic acid, and that a similar process occurs for the molecular ion under El. This gas-phase reaction is analogous to a solution reaction leading to phenyl-benzoxazoles. The proposed cyclization process, for which concurrent mechanisms were proposed (Scheme 38 depicts only the displacement reaction route), was corroborated by accurate mass measurements, tandem mass spectrometric experiments with comparison with reference ions, isotopic labeling and theoretical calculations. 

Pheiqrl-aathraniI 27, 72, II36. 2-Phenyl.benzoxazol 27. 72, 1235, II36. 2-a-Fnnl-ohinolin 27. 4. 

Oxy-2-phenyl-benzoxazol 27II88. 0-Oxy-2.pheiqrl-benzxand 27II91. 

Aoetyl-phenoxazin 27, 62. 2 Phenozymethyl benzoxazol 27,110. 3 [4-Methozy-phenyl]-indoxazen 27,116. 6 Methozy 2-phenyl-l nzozazol 87,117. 2-(4-Methozy-phenyl] benzoxazol 27 1253. 4-Oxy-2-beiizyl benzoxazol 27 II92. 6-Oxy 2-ben2yl nzoxazol 27 II92. 6-Oxy-2 o-t(dyl benzoxazol 27 II92. 6-Oi -2-p-tolyl-benzoxazol 27 II92. 6-Oxy-4-methyl-2-phenyl benzoxazol... 

Srinivasan et al. [124] reported the use of ILs as reaction media for synthesis of 2-phenyl benzoxazoles 78 by reaction of 2-aminophenols and benzoyl chlorides at RT (Scheme 35) they also recovered the IL, and reused it with a marginal loss in yield. 

This last tyj of nonsteroidal anti-inflammatory drugs, such as ibuprofen ([rac-2-(4-iso-butylphenyl) propionic acid], 5), flurbiprofen ([rac-2-((3-fluoro-4-phenyl)phenyl)propionic acid], 6), fenoprofen ([rac-2-(3-phenoxyphenyl)propionic acid], 7), suprofen ([rac-2-(4(2-fliienyloxo)phenyl)propionic acid, 8], carprofen ([rac-2-(6-chloro-9H-cabazolyl) propionic acid], 9), naproxen ([5(+)-2-(6-methoxy-2-naphthyl)propionic acid], 10), Dexketoprofen ([S(+)-2-(3-benzoylphenyl)propionic acid], 11), flunoxaprofen ([S(+)-2-(2(4-fluoro-phenyl)benzoxazol-5-yl)propionic acid], 12), or ketorolac ([5(+)-5-benzoyl-2,3-dihidro-1/i-pyrrolizine-l-carboxylic acid], 13, thromethamine salt marketed as Toradol), have a more promising future. 

---