The first aryne evolution from the reactions of selenonium salts with aryllithiums

The first example of the benzyne generation was found in the reactions of a lkynylselenonium salt 1a with 1.0 equiv. of phenyllithium in THF at room te mperature 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 1 8 and 19 in 19% yield (18:19=11:8) and a mixture of bitolyls 28 and 29 in 6 3% yield (28:29=2:1), respectively. The reaction mechanisms of these reacti ons are discussed. (C) 2000 Elsevier Science Ltd. All rights reserved.