surface acidic sites and the immobilized basic amines were weaker than the interactions between the SA and free amines. The catalytic performances of the SA-NR2 catalysts for various carbon-carbonbond-formingreactions, such as cyano-ethoxycarbonylation, the Michael reaction, and the nitro-aldol reaction, were investigated and compared with those of homogeneous and other heterogeneous catalysts. The
通过使酸性二氧化硅-氧化铝(SA)表面与具有氨基官能团的硅烷偶联剂反应,可以制备酸基双功能多相催化剂。通过固态13 C和29 Si NMR光谱,FT-IR光谱和元素分析对获得的SA负载的胺(SA-NR2)进行表征。固态NMR光谱显示,胺通过酸碱相互作用固定在SA表面。表面酸性位点和固定的碱性胺之间的相互作用比SA和游离胺之间的相互作用弱。SA-NR2催化剂对各种碳-碳键形成反应(如氰基-乙氧基羰基化,迈克尔反应和硝基-羟醛反应)的催化性能,进行了研究,并与均相和其他非均相催化剂进行了比较。与使用其他载体(例如SiO2和Al2O3)的非均相胺催化剂相比,SA-NR2催化剂对碳-碳键形成反应的催化活性更高。另一方面,均相胺在相似的反应条件下几乎不促进这些反应,并且SA-NR2的催化行为也不同于用作典型异质碱的MgO。提出了碳-碳键形成反应的酸碱双活化机理。均相胺很难在相似的反应条件下促进这些反
Asymmetric Cyanation of Aldehydes, Ketones, Aldimines, and Ketimines Catalyzed by a Versatile Catalyst Generated from Cinchona Alkaloid, Achiral Substituted 2,2′-Biphenol and Tetraisopropyl Titanate
Full investigation of cyanation of aldehydes, ketones, aldimines and ketimines with trimethylsilyl cyanide (TMSCN) or ethyl cyanoformate (CNCOOEt) as the cyanide source has been accomplished by employing an in situ generated catalyst from cinchona alkaloid, tetraisopropyl titanate [Ti(OiPr)4] and an achiral modified biphenol. With TMSCN as the cyanide source, good to excellent results have been achieved
Efficient synthesis in water of mixed carbonates of cyanohydrins from aromatic aldehydes
作者:Torres Domínguez Héctor Manuel、Maldonado Luis Ángel、Le Lagadec Ronan
DOI:10.1016/j.tetlet.2019.151414
日期:2020.1
An efficient preparation of cyanohydrin ethyl carbonates via cyanocarbonation of aromatic and hetero-aromatic aldehydes with sodium cyanide and ethyl chlorocarbonate using commercial surfactants (5 mol %) in aqueous media at low temperature afforded almost quantitative isolated yields (≥ 94 %) in 30 minutes. Aromaticaldehydes bearing electron-donating as well as electron-withdrawing groups have been
higher catalytic activity than that modified by hydrophilic ethanolamine groups. PANBTF can efficiently and rapidly catalyze the cyanation reaction of benzaldehyde and ethyl cyanoformate in water with a yield of 94 % at room temperature within 40 min. Moreover, a mechanism promoted by the hydrophobic microenvironment has been proposed to explain the high and specific catalytic activity of PANBTF. In addition
N,N-Dimethylpyridin-4-Amine Mediated Protocol for Cyanoethoxycarbonylation of Aldehydes Under Solvent-Free Conditions
作者:Noor-ul H. Khan、Santosh Agrawal、Rukhsana I. Kureshy、Prasanta K. Bera、Sayed H. R. Abdi、Hari C. Bajaj
DOI:10.1007/s10562-010-0355-7
日期:2010.7
N, N-Dimethylpyridin-4-amine (DAMP) (10 mol%) was successfully employed as catalyst for cyanoethoxycarbonylation of aromatic and aliphatic aldehydes at room temperature under solvent free condition to give corresponding ethylcyanocarbonates in excellent isolated yield (up to 95%) in 15-90 min. Simple experimental conditions and product isolation procedure has made this protocol quite attractive for the synthesis of ethylcyanocarbonates in an environment-friendly manner.