Preparation of ?,?-Dibromocyclobutanones from Olefins: A simple procedure for the regioselective functionalization of olefins
作者:H�l�ne Chaumeil、Claude Le Drian
DOI:10.1002/hlca.19960790416
日期:1996.6.26
of tribromoacetyl bromide in the presence of POCl3. Under these conditions, the cycloaddition of dibromoketene with olefins 5 yields α,α-dibromocyclobutanones 2, which are cleaved with alkoxides to yield β-dibromomethyl esters 4. Several examples are given. For monosubstituted olefins, the functionalization is regioselective, the methoxycarbonyl group being introduced at the terminal C-atom.
二溴乙烯酮是通过在POCl 3存在下三溴乙酰溴的原位Zn脱卤制备的。在这些条件下,二溴乙烯酮与烯烃5的环加成反应会生成α,α-二溴环丁酮2,后者会被醇盐裂解,生成β-二溴甲基酯4。给出了几个例子。对于单取代的烯烃,官能化是区域选择性的,甲氧基羰基被引入末端C-原子。