在此,我们报道了由镍分子催化剂介导的碳酸炔丙酯催化还原为丙二烯。该催化系统使用光作为驱动力,胺作为唯一的氢源。与其他催化方法相反,该过程的进行无需金属氢化物物质的中介。过渡金属催化还原过程中常见的途径被涉及一系列电子转移和质子转移的途径所取代。使用这种催化方法,可以在温和条件下获得多种丙二烯。实验研究支持三烷基胺作为还原剂和质子源的双重作用,并揭示了该反应的关键机理特征。提出了Ni( II ) 联烯基中间体的关键原脱镍步骤来解释还原过程。最后,我们还证明选择性 S N 2 ' 还原过程也可以通过电化学方法有效驱动。
Catalytic One-Pot Synthesis of Trisubstituted Allenes from Terminal Alkynes and Ketones
作者:Qi Liu、Xinjun Tang、Yujuan Cai、Shengming Ma
DOI:10.1021/acs.orglett.7b02443
日期:2017.10.6
one-pot synthesis of trisubstituted allenesfrom readily available terminal alkynes and ketones is realized. A wide range of trisubstituted allenes may be synthesized efficiently via this method. Preliminary mechanistic studies revealed that CuI and Ti(OEt)4 are in charge of the formation of propargylic amine, while ZnBr2 is responsible for the transformation from propargylic amine to allene.
Chromium(0)-Promoted [6π + 2π] Cycloadditions of Allenes with Cycloheptatriene
作者:James H. Rigby、Stéphane B. Laurent、Zeeshan Kamal、Mary Jane Heeg
DOI:10.1021/ol802401a
日期:2008.12.18
Photoinitiated [6pi + 2pi] cycloadditions of allenes with (eta(6)-cycloheptatriene)tricarbonylchromium(0) (1) are described. An example of asymmetric induction obtained by reaction of 1 with a chiral 1,3-disubstituted allene is also reported.