The synthesis of the highly reactive 1,4-unsymmetrically substituted butatrienes 12a-c is described. When employing a strict synthetic protocol, these alkatrienes react with lithium metal to 3,4-dilithio-1,2-butadienes 20a-c as stable intermediates. The structure of 20 is supported by IR and NMR spectroscopic evidence. The same dianionic intermediate can be prepared in one case by double deprotonation
1-Bromobicyclo[1.1.0]butanes and strong bases: products and mechanism
作者:Axel Düker、Günter Szeimies
DOI:10.1016/s0040-4039(00)89189-3
日期:1985.1
Treatment of the bromobicyclo[1.1.0]butanes (=4)(=a) - (=c) with LDA led to the formation of the 1,2,3-butatrienes (=6) which were isomerized by excess base to the alkynes (=8). Reaction of [1-12-C](=4)(=c) with LDA afforded [3-12-C](=8)(=d), indicating that bicyclo[1.1.0]but-1(3)-ene (=5) was not an intermediate.