O-Substituted Alkyl Aldehydes for Rhodium-Catalyzed Intermolecular Alkyne Hydroacylation: The Utility of Methylthiomethyl Ethers
摘要:
Combining a-methylthiomethyl (MTM) ether substituted aldehydes and 1-alkynes in the presence of [Rh(dppe)]CIO(4) results in efficient intermolecular alkyne hydroacylation to deliver alpha-O-MTM-substituted enone products. The product MTM ethers can be converted to the free hydroxyl group either in situ, by the addition of water to the completed reaction, or in a separate operation, by the action of silver nitrate.
Aza-crown compounds synthesised by the self-condensation of 2-amino-benzyl alcohol over a pincer ruthenium catalyst and applied in the transfer hydrogenation of ketones
作者:Shanshan Zhang、Zheng Wang、Qianrong Cao、Erlin Yue、Qingbin Liu、Yanping Ma、Tongling Liang、Wen-Hua Sun
DOI:10.1039/d0dt03257c
日期:——
conformation structure of 3. These aza-crown compounds have been explored to study ferric initiation of transferhydrogenation (TH) of ketones into their corresponding secondary alcohols in the presence of 2-propanol with a basic t-BuOK solution, achieving a high conversion (up to 95%) by a ferric complex with 2 in a low loading (0.05 mol%).
Catalytic Hydrosilylation of Ketones Using a Co/Zr Heterobimetallic Complex: Evidence for an Unusual Mechanism Involving Ketyl Radicals
作者:Wen Zhou、Seth L. Marquard、Mark W. Bezpalko、Bruce M. Foxman、Christine M. Thomas
DOI:10.1021/om301194g
日期:2013.3.25
tris(phosphinoamide)-linked heterobimetallic Co/Zr complex (THF)Zr(MesNPiPr2)3CoN2 (1) has been investigated as a catalyst for the hydrosilylation of ketones with PhSiH3. Catalytic activity superior to monometallic Co or Zr analogues has been observed, demonstrating the importance of cooperative reactivity between Co and Zr. Upon examining stoichiometric reactions, complex 1 was found to be unreactive toward PhSiH3
已经研究了三(膦酰胺)连接的异双金属Co / Zr络合物(THF)Zr(MesNP i Pr 2)3 CoN 2(1)作为酮与PhSiH 3进行硅氢加成反应的催化剂。已观察到优于单金属Co或Zr类似物的催化活性,表明Co和Zr之间协同反应的重要性。通过检查化学计量反应,发现复合物1对PhSiH 3无反应,这表明该机理不同于典型的Chalk–Harrod型氢化硅烷化途径。相反,1易与酮反应,在二苯甲酮的情况下,分离出自由基偶联产物[(Ph 2 CO)Zr(MesNP i Pr 2)3 CoN 2 ] 2(3),这表明与Zr结合的酮基自由基具有中间性分段。提出了一种基于自由基的氢化硅烷化机制,该机制涉及氢原子从PhSiH 3转移到Zr结合的酮基自由基上。
Zinc(ii)-catalyzed Grignard additions to ketones with RMgBr and RMgI
Highly efficient alkylations and arylations of ketones with Grignard reagents (RMgBr and RMgI) have been developed using catalytic ZnCl(2), Me(3)SiCH(2)MgCl, and LiCl. Tertiary alcohols were obtained in high yields with high chemoselectivities, while minimizing undesired side products produced by reduction and enolization.
The addition of organometallic reagents to carbonyl compounds has become a versatile method for synthesizing tertiary and secondary alcohols via carbon−carbon bond formation. However, due to the lack of good nucleophilicity or the presence of strong basicity of organometallic reagents, the efficientsynthesis of tertiary alcohols from ketones has been particularly difficult and, thus, limited. We recently
向羰基化合物中添加有机金属试剂已成为通过碳-碳键形成合成叔醇和仲醇的通用方法。然而,由于缺乏良好的亲核性或存在有机金属试剂的强碱性,由酮有效地合成叔醇特别困难并且因此受到限制。我们最近使用ZnCl 2,Me 3 SiCH 2开发了格氏试剂(RMgX:R =烷基,芳基; X = Cl,Br,I),对酮进行了高效的催化烷基化和芳基化反应MgCl和LiCl,可有效减少有问题的副反应。原则上,对于加成羰基化合物,RMgBr和RMgI的反应性不如RMgCl。因此,这种新颖的方法与均相催化的ZnCl 2 ·我3 SICH 2 MgCl·LiCl是相当有吸引力的,因为RMgBr和RMGI,其易于制备和/或可商购的,如RMgCl,可以成功地应用。除酮和醛以外,醛亚胺也有效地用于该催化反应,并以高收率获得了相应的仲胺。关于β-甲硅烷基效应和盐效应的机理细节,原位制备[R(Me 3 SiCH 2)2 Zn] -
Substitution of the acetoxy groups of dialkoxymethylacetates by organometallic reagents: a route to allyl-, propargyl-, homoallyl-, homopropargyl- and α-stannylacetals
The substitution of the acetoxy groups of dialkoxymethylacetates by organometallicreagents has been examined in a search for new methods of preparing functional acetals. The efficiency of the substitution of the acetoxy group is highly dependent on the nature of the organometallicreagents: soft nucleophiles with strong electrophilic assistance by the counterion are the best reagents. Allyl-, propargyl-