The First Aryne Evolution from the Reactions of Selenonium Salts with Aryllithiums
摘要:
The first example of the benzyne generation was found in the reactions of alkynylselenonium salt 1a with 1.0 equiv. of phenyllithium in THF at room temperature for 3 h. The formation of the aryne intermediate was confirmed in the reactions of alkynylselenonium salt 1b and tri-p-tolylselenonium salt 6b with tolyllithium, which gave a mixture of alkynylbiphenyl derivatives 18 and 19 in 19% yield (18:19=11:8) and a mixture of bitolyls 28 and 29 in 63% yield (28:29=2:1), respectively. The reaction mechanisms of these reactions are discussed. (C) 2000 Elsevier Science Ltd. All rights reserved.
The reaction of diphenyl(phenylethynyl)selenonium salt 1a with 1.0 equiv. of phenyllithium afforded 1,4-diphenylbutadiyne 5 and 1-(o-biphenylyl)-2-phenylethyne 7 in 25% and 15% yields, respectively. The latter product 7 was formed via the benzyneintermediate.
The thermal decomposition of benzenediazonium-2-car☐ylate in the presence oftrans-(phenylethynyl)(trichlorovinyl)bis(triethylphosphine)nickel(II), (I), in dichloromethane affords [2-(phenylethynyl)phenyl] (trichlorovinyl)bis(triethylphosphine)nickel(II) < (III). Also present in the product mixtures way 2-(phenylethynyl)(trichlorovinyl)benzene, (IV), which was shown to be formed from (III) under the