A Cross Metathesis Based Protocol for the Effective Synthesis of Functionalised Allyl Bromides and Chlorides
作者:Pier Giorgio Cozzi、Achille Umani-Ronchi、Marco Bandini、Sebastiano Licciulli
DOI:10.1055/s-2004-815936
日期:——
Functionalised allyl halides, useful starting materials for the preparation of substituted organometallic reagents can be simply obtained by a straightforward approach. Hoveyda’s ruthenium carbene catalyst 3, used in catalytic amount (2 mol%), is able to promote the cross metathesis of allyl bromide and chloride with a variety of different substituted olefins giving the corresponding functionalised allyl halides in satisfactory yields. trans-Olefins are obtained as major diastereoisomers reaching 90:10 (trans:cis) ratio when allyl chloride is used as the metathesis partner. This reaction represents a simple and accessible way for the preparation of valuable precursors for functionalised organometallic reagents. In particular, the use of functionalised allyl bromides (10b and 13) in the enantioselective Nozaki-Hiyama reaction promoted by [Cr(Salen)Cl] is presented.
功能化的烯丙基卤化物,作为制备取代有机金属试剂的有用起始材料,可以通过一种直接的方法简单地获得。Hoveyda的钌卡宾催化剂3,以催化量(2 mol%)使用,能够促进烯丙基溴和氯与多种不同取代烯烃的交叉复分解反应,以令人满意的产率得到相应的功能化烯丙基卤化物。使用烯丙基氯作为复分解反应伙伴时,主要得到trans-烯烃的非对映异构体,比例达到90:10(trans:cis)。这一反应为制备功能化有机金属试剂的有价值前体提供了一种简单且易行的方法。特别是,展示了功能化烯丙基溴(10b和13)在[Cr(Salen)Cl]促进的手性选择性野崎-日山反应中的应用。