N-Heterocyclic carbenes as ligands in palladium-catalyzed Tsuji–Trost allylic substitution
作者:Yoshihiro Sato、Taro Yoshino、Miwako Mori
DOI:10.1016/j.jorganchem.2005.07.043
日期:2005.12
reaction. Allylicsubstitutionusing a Pd–NHC complex differed from that using a Pd–phosphine complex as follows: (1) the reaction using a Pd–NHC complex required elevated temperature (50 °C or reflux in THF), (2) allylic carbonates were inert to a Pd–NHC complex, and (3) nitrogen nucleophiles such as sulfonamide and amine did not react with allylic acetate. It was also found that allylicsubstitution with
研究了使用N-杂环卡宾作为配体的Pd(0)催化的烯丙基取代(即Tsuji-Trost反应)。业已证明,在咪唑-2-亚烷基骨架中的氮原子上带有庞大的芳香环的咪唑鎓盐2d适合用作配体前体,并且Pd 2 dba 3-咪唑鎓盐2d -Cs 2 CO 3该系统对于在该反应中生产Pd-NHC催化剂非常有效。使用Pd-NHC络合物的烯丙基取代与使用Pd-膦络合物的烯丙基取代具有以下区别:(1)使用Pd-NHC络合物的反应需要升高的温度(50°C或在THF中回流),(2)烯丙基碳酸酯对Pd-NHC络合物呈惰性,并且(3)氮亲核试剂(如磺酰胺和胺)不会与乙酸烯丙酯反应。还发现使用Pd-NHC催化剂用软亲核试剂进行烯丙基取代是通过整体保留构型而进行的,从而以立体特异性方式得到产物,立体化学反应过程显然与使用Pd-膦的反应相同。复杂的。
Single-step preparation of allylic sulfides having 1-phenyltetrazole-5-thio group from allylic alcohols using ,′-BIS(1-phenyl-1-tetrazol-5-YL) dithiocarbonate and reactions involving the allylic sulfides
The reaction of allylicalcohols and ,′-bis(1-phenyl-1-tetrazol-5-yl) dithiocarbonate () gave allylic sulfides having 1-phenyltetrazole-5-thio group in a single step. Furthermore, these allylic sulfides could be applied to carbon-carbon bond and carbon-sulfur bond formations by using Grignard reagents or carbanions in the presence of a catalytic amount of copper(I)bromide or palladium (0), respectively
Pd-Catalyzed Allylic Substitution Using Nucleophilic N-Heterocyclic Carbene as a Ligand
作者:Yoshihiro Sato、Taro Yoshino、Miwako Mori
DOI:10.1021/ol026961v
日期:2003.1.1
A nucleophilic N-heterocyclic carbene has been successfully used in a Pd(0)-catalyzed allylic substitution for the first time. It was found that allylic substitution with a soft nucleophile using a Pd-carbene catalyst proceeds via retention of configuration, the stereochemical reaction pathway being the same as that of the reaction using a Pd-phosphine complex.
Chirality transfer in palladium catalyzed reactions of allylammonium salts
Optically active 1-isobutyl-2(Z)-butenyltrimethylammonium iodide (10) underwent allylation with dimethyl sodiomalonate in the presence of a palladium(0) catalyst. The reaction proceeded predominantly with 1,3 transposition and with inversion of configuration due probably to a prior isomerization from anti to syn-pi-allylpalladium intermediate (14-->15). The stereochemistry observed in the reaction with phenylzinc chloride was opposite to that with the soft nucleophile.
TSUBOYAMA, KANOKO;TAKEDA, KAZUYOSHI;TORII, KATSUMI;OGURA, HARUO, CHEM. AND PHARM. BULL., 38,(1990) N, C. 2357-2363