Catalytic Asymmetric Cyano-Ethoxycarbonylation Reaction of Aldehydes Using a Novel <i>C</i><sub>2</sub>-Symmetric Chiral <i>N</i>,<i>N</i>′-Dioxide Titanium Complex
作者:Xiaoming Feng、Qinghan Li、Lu Chang、Xiaohua Liu
DOI:10.1055/s-2006-947322
日期:2006.7
The asymmetric addition of ethyl cyanoformate to a range of aldehydes was efficiently catalyzed by a easily prepared C 2 -symmetric chiral N,N'-dioxide-Ti(IV) complex in high yields with up to 90% ee under mild conditions. A linear effect between the enantiopurity of the ligand and the enantiopurity of the product was observed.
氰基甲酸乙酯与一系列醛的不对称加成被一种易于制备的 C 2 -对称手性 N,N'-二氧化钛-Ti(IV) 配合物有效催化,在温和条件下的收率高达 90%。观察到配体的对映纯度和产物的对映纯度之间存在线性效应。
Asymmetric Cyanoethoxycarbonylation of Aldehydes Catalyzed by Heterobimetallic Aluminum Lithium Bis(binaphthoxide) and Cinchonine
catalytic asymmetriccyanoethoxycarbonylation of aldehydes was achieved by 10 mol % cinchonine with 10 mol % heterometallic (S)-aluminum lithiumbis(binaphthoxide), which gave the cyanohydrins ethyl carbonates in excellent isolated yields (up to 99 %) with moderate to high enantioselectivities (up to 95 % ee) under mild conditions (at −20 °C). Especially, the solid aluminumlithiumbis(binaphthoxide) free
Asymmetric cyano-ethoxycarbonylation of aldehydes catalyzed by self-assembled titanium catalyst
作者:Shaohua Gou、Xiaohua Liu、Xin Zhou、Xiaoming Feng
DOI:10.1016/j.tet.2007.05.060
日期:2007.8
aromatic aldehydes, aliphatic aldehydes, and α,β-unsaturated aldehydes were found to be suitable substrates in the presence of the self-assembled titanium catalyst (5 mol % 1h, 5 mol % 2b, and 5 mol % Ti(OiPr)4). The desired cyanohydrin ethyl carbonates were afforded with high isolated yields (up to 95%) and moderate to good enantioselectivities (up to 92% ee) under mild conditions (at −15 °C). A possible
已经开发了一种基于钛配合物的新型自组装催化剂,用于醛的有效对映选择性氰基-乙氧基羰基化。自组装催化剂很容易由(R)-3,3'-双((甲基((S)-1-苯基乙基)氨基)甲基)-1,1'-联萘-2,2'-二醇(1h),N -((1S,2R)-2-羟基-1,2-二苯乙基)乙酰胺(2b)和钛酸四异丙酯(Ti(O i Pr)4)。发现在自组装钛催化剂(5 mol%1h,5 mol%2b,和5mol%的Ti(O i Pr)4)。在温和的条件下(-15℃)以较高的分离产率(最高95%)和中等至良好的对映选择性(最高92%ee)提供了所需的氰醇乙酯碳酸酯。提出了基于实验观察的可能的催化循环。
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
Enantioselective and diastereoselective syntheses of cyanohydrin carbonates
作者:Yuri N. Belokon'、William Clegg、Ross W. Harrington、Eisuke Ishibashi、Hiroshi Nomura、Michael North
DOI:10.1016/j.tet.2007.07.016
日期:2007.9
cocatalyst are developed. Under these conditions, two chiral cyanoformates also reacted with aldehydes to give cyanohydrin carbonates. The stereochemistry of this process is predominantly determined by the stereochemistry of the titanium(salen) catalyst and the stereochemistry of two of the cyanohydrin carbonates was confirmed by X-ray crystallography. In a further extension of the chemistry, a homogeneous