Zirconacycle-mediated synthesis of carbocycles

Direct transformation of five-membered zirconacycles to carbocyclic compounds is of great synthetic interest. The reaction of zirconacycles with electrophiles containing at least two reactive functional groups or an oxidant affords various carbocycles through cross coupling, addition, and/or oxidative coupling reactions. In this paper, we present our recent results on the zircona-cycle-mediated formation of carbocycles, including: (1) 1,1-cycloaddition of oxalyl dichloride with zirconacycles; (2) benzoqui-none-promoted coupling of zirconacyclopentadienes in the presence of CuCl; (3) cycloaddition of zirconacyclopentadienes to quinones; (4) cycloaddition of zirconacyclopentadiene with 2-bromoacrylate, 2-bromoacrylaldehyde and 3-bromofuran-2,5-dione in the presence of CuCl; (5) one-pot coupling of two alkynes and an alkene to form cyclohexene derivatives via zirconacyclopen-tadienes; and (6) dianionic cycloaddition of decatetraenes with esters or acyl chlorides to form nine-membered carbocycles.     

关于烯烃加成反应历程的讨论

介绍了有机化学教材中亲电加成反应的立体化学部分一个值得得商榷的问题.