1,2-Bis(diphenylphosphino)carborane As a Dual Mode Ligand for Both the Sonogashira Coupling and Hydride-Transfer Steps in Palladium-Catalyzed One-Pot Synthesis of Allenes from Aryl Iodides
作者:Hiroyuki Nakamura、Takaya Kamakura、Shinya Onagi
DOI:10.1021/ol060538v
日期:2006.5.1
One-pot allene synthesis from aryl iodides 1 and propargyldicyclohexylamine 2 proceeded in the presence of Pd(2)(dba)(3).CHCl(3) catalyst (2.5 mol %), 1,2-bis(diphenylphosphino)carborane 5 (10 mol %), CuI (15 mol %), and Et(3)N (150 mol %) to give the corresponding allenes 4 in good to high yields. Electron-deficient bidentate phosphines, such as 1,2-bis(diphenylphosphino)carborane 5 and (C(6)F(5))
Ligand Controlled Highly Selective Copper-Catalyzed Borylcuprations of Allenes with Bis(pinacolato)diboron
作者:Weiming Yuan、Shengming Ma
DOI:10.1002/adsc.201100929
日期:2012.7.9
Copper‐catalyzed highlyselectiveborylcuprations of allenes with bis(pinacolato)diboron produce two different types of alkenylboranes by applying a ligand effect. In the presence of tris(para‐methoxyphenyl)phosphine [P(C6H4OMe‐p)3], the reaction of aryl‐1,2‐dienes affords 2‐alken‐2‐yl boronates as the only product with exclusive Z‐geometry; the regioselectivity is switched to afford the 1‐alken‐2‐yl
铜催化的具有双(频哪醇)二硼烷的丙二烯的高选择性硼烷基cup通过施加配体效应产生两种不同类型的烯基硼烷。在存在三(对-甲氧基苯基)膦[P(C 6 H 4 OMe- p)3 ]的情况下,芳基1,2-二烯的反应提供2-烯丙基-2-基硼酸酯作为唯一的独家产品Z几何 当使用二齿膦2,2'-双(二苯基膦基)联苯作为配体时,区域选择性切换为主要产物1-烯丙基-2-基硼酸酯。
Development of Highly Chemoselective Bulky Zincate Complex,<i>t</i>Bu<sub>4</sub>ZnLi<sub>2</sub>: Design, Structure, and Practical Applications in Small-/Macromolecular Synthesis
We present full details of the unique reactivities of the newly developed dianion-type bulky zincate, dilithium tetra-tert-butylzincate (tBu(4)ZnLi(2)). With this reagent, halogen-zinc exchange reaction of variously functionalized haloaromatics and anionic polymerization of N-isopropylacrylamide (NIPAm)/styrene with excellent chemoselectivity were realized. Halogen-zinc exchange reaction followed by
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.
Mono- and 1,3-disubstituted allenes were synthesized from the corresponding propargylamines via palladium-catalysed hydride-transferreaction. In the current transformation, propargylic amines can be handled as allenyl anion equivalents and introduced into various electrophiles to be transformed into allenes under palladium-catalyzed conditions.