3-Phenylfurane

Under cathodic reduction condition, 2-bromo-2-cyanoacetophenone is transformed into 5-amino-4-benzoyl-3-phenylfuran-2-carbonitrile in good yield <00H(53)1337>. Cyanoketones react with glycolate under Mitsunobu conditions to produce vinyl ethers which give rise to 3-... 

To an acetone solution (6 ml) of the preceding (methylthio)furan (190 mg, 1 mmol) was added Raney nickel W-7 (prepared from 1 g of Raney Ni alloy) in ethanol (12 ml) and the solution was stirred for 30 min at room temperature. After filtration and washing (ethanol) of the Raney Ni, the filtrate was concentrated in vacuo. To the residue was added brine (20 ml) and the solution was extracted with ether. The combined ethereal solution was dried (MgS04), concentrated, and subjected to chromatography on Florisil (elution with pentane) to give 3-phenylfuran (42%), colourless crystals, m.p. 51-57°C. 

Dihydro-3/3-methyl-2/3-phenylfuran 2.3- Dihydro-3a-methyl- CC14 5.42 —3.1 5.05 6.38 74BSF197... 

The preparation of 3-phenylfuran from 3-hydroxy-3-phenyl-tetrahydrofuran is described by Wynberg.48 The dehydrogenation was effected by sulfur in dimethylformamide. Sulfur is equally suitable for the preparation of 3,4-diphenylfuran, which is obtained in 25% yield.47 Potassium ferricyanide has also been successfully employed for the dehydrogenation of 3-carbethoxytetrahydrofuran.48... 

The 3-methylfuran was obtained by subsequent hydrolysis and decarboxylation. 3-Phenylfuran could be prepared analogously via 3-phenyl-2-furoic ester. 

Oxopentanals may be synthesized from allylic alcohols by 3,3-sigmatropic rearrangement of their vinyl ethers, and subsequent oxidation of the terminal double bond. ° Cinnamyl alcohol (31) was converted to the allyl vinyl ether (32), which was subjected to Claisen rearrangement to give 3-phenyl-4-pentenal (33) in 30% yield. Oxidation of the terminal double bond of (33) gave 3-phenyl-4-oxopentanal (34) in 76% yield, which was converted to 2-methyl-3-phenylfuran (35) in quantitative yield (Scheme 9). 

Wynberg2 showed that 3 -phenyl-2,5-dihydrofurane can be dehydrogenated to 3-phenylfurane in high yield by refluxing a homogeneous solution in dimethyl-formamide containing 2-3% sulfur for 30 min. and steam-distilling the product. 

PHE592 3-phenylfuran opioid receptor ligand 1994BMCL4 2527... 

Ethyl diazoacetate added dropwise during ca. 7.5 hrs. with stirring at 90° under Ng to a mixture of 1-phenylpropyne, anhydrous cupric sulfate, and cyclohexane, the temp, reduced to 70° after Ng-evolution has started 5-ethoxy-2-methyl-3-phenylfuran. Y 48% based on 1-phenylpropyne consumed. I. A. D ya-konov and M, I. Komendatov, 7K.. 31, 3881 (1961) G. A. 57, 8405f benzyne as dipolarophile s. R. Huisgen and R. Knorr, Naturwissenschaften 48, 716 (1961). 

TiCl4 added dropwise at -78° under argon to a soln. of 2-bromobutyraldehyde dimethyl acetal in methylene chloride, then a soln. of 2-trimethylsiloxy-l-phenyl-1-propene in the same solvent added dropwise, stirred an additional 2 hrs. at -78°, treated with a cold pH 6.7 phosphate buffer soln. of KH2PO4 and NagHP04, and the soln. of the resulting intermediate in toluene refluxed 8 hrs. under argon -> 5-ethyl-2-methyl-3-phenylfuran. Y 82%. F. e. s. T. Mukaiyama, H. Ishihara, and K. Inomata, Chem. Lett. 1975, 527 first step s. a. ibid. 1975, 531. 

Oppenlander, T. and Schonholzer, R, Synthesis, reactivity and application as chiral auxiliaries of the novel (3R)- and (3S)-4,5-dihydro-3-hydroxy-4,4,5,5-tetramethyl-3-phenylfuran-2(3H)-ones in the Paterno-BUchi reaction, Helv. Chim. Acta, 72, 1792, 1989. 

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