Benzyne butyl ether

Benzyne, intermediate in preparation of phenyl t butyl ether, 46, 90 methods for generation of, 46, 112 trapping by tetraphenylcyclopenta-dienone, 46,112... 

Cram and co-workers describe a procedure for the conversion of bromo-benzene into phenyl t-butyl ether by reaction with potassium t-butoxide in dimethyl sulfoxide at 125-130° for 1 minute. Benzyne is assumed to be an intermediate. 

In the case of 1,3-diphenylisoindole (29), Diels-Alder addition with maleic anhydride is readily reversible, and the position of equilibrium is found to be markedly dependent on the solvent. In ether, for example, the expected adduet (117) is formed in 72% yield, whereas in aeetonitrile solution the adduet is almost completely dissociated to its components. Similarly, the addition product (118) of maleic anhydride and l,3-diphenyl-2-methjdi.soindole is found to be completely dissociated on warming in methanol. The Diels-Alder products (119 and 120) formed by the addition of dimethyl acetylene-dicarboxylate and benzyne respectively to 1,3-diphcnylisoindole, show no tendency to revert to starting materials. An attempt to extrude carbethoxynitrene by thermal and photochemical methods from (121), prepared from the adduct (120) by treatment with butyl-lithium followed by ethyl chloroform ate, was unsuccessful. 

Bromobenzene Benzyne tert-Butyl phenyl ether... 

O-Phenylation of tertiary alcohols can be realized through reaction with pentaphenylbismuth (4), a benzyne intermediate being involved. r rf-Butyl phenyl ether (80) was also obtained in rather low yields in the reaction of triphenylbismuth diacetate with rerr-butyl alcohol used as solvent in the presence of potassium carbonate or by reaction of triphenylbismuth dichloride with lithium ten-... 

When the dichloro diaryl ether 112 was treated with x-BuIi, a dibenzyne was generated and subsequently trapped by 2-methoxyfuran, affording dinaphthyl ethers 113 and 114 after aromatization (Scheme 12.34) [64]. The monocycloadducts 115 and 116 were also present in the reaction mixture. With carefijl control of the stoichiometry of the butyl lithium, an iterative double benzyne-furan Diels-Alder reaction was achieved between benzyne precursor l,4-difluoro-2,5-dime-thoxybenzene and two different furans. 

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