Formation de derives cyclopentaniques assistee par une espece hydrure de palladium : Aspects synthetiques et mecanisme
摘要:
In the presence of a palladium(0) complex and potassium t-butoxide, the acetylenic compounds 2 bearing in delta a nucleophilic functionality are smoothly transformed with excellent yields, either into 2,2-difunctionalized methylene cyclopentanes or into monofunctionalized 2-methylcyclopentenes. Each of these compounds can be specifically obtained depending on the choice of the experimental conditions.A set of diverse reactions involving mainly potassium hydride as the base showed clearly that HPdOtBu is not the active catalytic species which is mainly a sigma-ethynylpalladium hydride formed by the metal insertion in the acetylenic carbon hydrogen bond.
Hydro(trispyrazolyl)borato-Ruthenium(II) Diphosphinoamino Complex-Catalyzed Addition of β-Diketones to 1-Alkynes and Anti-Markovnikov Addition of Secondary Amines to Aromatic 1-Alkynes
作者:Hung Wai Cheung、Chau Ming So、Kwok Hung Pun、Zhongyuan Zhou、Chak Po Lau
DOI:10.1002/adsc.201000567
日期:2011.2.11
[Tp=hydro(trispyrazolyl)borate] catalyzes the Markovnikov addition of β-diketones to unactivated 1-alkynes in good to excellent yields. The reaction proceeds under solvent-free and additive-free conditions and the catalyst loading can be reduced down to 0.4 mol%. Complex I (1 mol%) also catalyzes the addition of secondaryamines to aromatic terminal alkynes, unusual anti-Markovnikov products are exclusively
氢(三吡唑基)硼酸钌(II)二膦氨基配合物TpRu [4-CF 3 C 6 H 4 N(PPh 2)2 ](OTf)(I)[Tp =氢(三吡唑基)硼酸]催化Markovnikov加成β-二酮与未活化的1-炔具有良好至极好的收率。反应在无溶剂和无添加剂的条件下进行,催化剂的负载量可降低至0.4mol%。配合物I(1摩尔%)还催化向芳族末端炔烃中添加仲胺,从而形成了独特的反马尔科夫尼科夫产物。
Development of an enantioselective amine–silver co-catalyzed Conia-ene reaction
The development of a novel cooperative catalytic system for an amine–silver co-catalyzed Conia-ene reaction of alkyne-tethered C–H-acidic compounds is reported.
An original multi-cooperative catalytic approach was developed by combining metal–ligandcooperation and Lewis acidactivation. The [(SCS)Pd]2 complex featuring a non-innocent indenediide-based ligand was found to be a very efficient and versatilecatalyst for the Conia-ene reaction, when associated with Mg(OTf)2. The reaction operates at low catalytic loadings under mild conditions with HFIP as a