钐试剂在合成中的应用I. 金属钐作用下烯丙基和苄基卤代物与羰基化合物的反应

本文研究了金属钐作用下的Barbier型反应。结果表明, 经氯化汞活化的金属钐对酮类化合物与烯丙基或苄基卤代物的反应很有效, 可高产率地生成叔醇。此反应有很好的区位选择性和化学选择性, 与α, β-不饱和酮的反应未发现1, 4-加成产物生成, 与环上有卤素(Br, Cl)取代的芳香酮反应, 取代基不受影响。产物的形成可能通过了有机钐中间体。

Samarium in organic synthesis. I. reaction of allyl or benzyl halides with carbonyl compounds promoted by samarium metal

Samarium metal promoted Barbier-type reactions have been investigated. Samarium metal (activated by HgCl2) is an effective reagent for allylation or benzylation of ketones. The corresponding tertiary alcs. are obtained in satisfactory yields. This reaction is regioselective and chemoselective. When reaction with a,b-unsatd. ketones no. 1,4-addn. products were found. The reactive groups (such as Br, Cl and methoxyl) or aromatic ketones in this reaction condition remain unchanged. An organosamarium intermediate reaction mechanism has been suggested.