and cyclohexane) and the relative rate of O—H insertion into methanol to stereospecific cyclopropanation of the olefin to C—H insertion into cyclohexane are calculated from the ratios of products and substrates. It is found (i) that the reactivities of the substrates decrease in the order of methanol, olefin and cyclohexane and (ii) that electron-donating substituents generally lead to reaction with
Highly Efficient and Enantioselective α-Arylation of Cycloalkanones by Scandium-Catalyzed Diazoalkane-Carbonyl Homologation
作者:Jason Kingsbury、Victor Rendina、Hilan Kaplan
DOI:10.1055/s-0031-1289650
日期:2012.3
Functionalized α-tertiary and -quaternary 2-arylcycloalkanones are rapidly accessed by scandium(III) triflate-catalyzed diazoalkane-carbonyl homologations. Recent developments have allowed for carbon insertion reactions to be performed with catalyst loadings as low as 0.5 mol% on scales up to 5 mmol. Pairing readily available bis- and tris(oxazoline) based ligands with scandium triflate allows access to arylated medium ring carbocycles with enantioselectivities up to 98:2 er and >98% yield. The formal C-C insertion of aryldiazomethanes into unsubstituted cycloalkanones provides a single-step solution to the ongoing challenge of α-arylation.
Titration of Nonstabilized Diazoalkane Solutions by Fluorine NMR
作者:Victor L. Rendina、Jason S. Kingsbury
DOI:10.1021/jo202214e
日期:2012.1.20
A new protocol for titrating nonstabilized diazoalkane solutions by quantitative 19F NMR is reported. An excess of 2-fluorobenzoic acid dissolved in CDCl3 is treated with the diazoalkane solution at a low temperature, immediately forming the corresponding 2-fluorobenzoate ester upon warming. A significant difference in the 19F chemical shift between the ester and acid is seen, allowing facile and accurate
报道了通过定量19 F NMR滴定不稳定的重氮烷溶液的新方案。用重氮烷溶液在低温下处理溶解在CDCl 3中的过量的2-氟苯甲酸,在加热后立即形成相应的2-氟苯甲酸酯。观察到酯和酸之间在19 F化学位移方面存在显着差异,从而可以轻松,准确地积分来确定滴度。该过程安全,快速,并且可以高精度指示活性重氮烷浓度。
Sc(OTf)3‐Catalyzed Synthesis of 3‐Substituted Lawsones through a Buchner‐Curtius‐Schlotterbeck Reaction
作者:Sailam Sri Gogula、Dasari Vijaya Prasanna、B. Sridhar、Ch. Abraham Lincoln、P. Muralidhar Reddy、B. V. Subba Reddy
DOI:10.1002/ejoc.202400362
日期:2024.8.19
An efficient method has been developed for the synthesis of 3-substituted lawsones using 10 mol % Sc(OTf)3 in toluene at −78 °C through a Buchner-Curtius-Schlotterbeck reaction. This method is simple and convenient to the synthesis of pharmaceutically relevant 3-substituted lawsones in high to excellent yields.
开发了一种有效的方法,使用 10 mol% Sc(OTf) 3在甲苯中,在 -78 °C 下通过布赫纳-库尔蒂斯-施洛特贝克反应合成 3-取代的指甲花酮。该方法简单方便,可以高收率合成药学相关的3-取代指甲花酮。
Tomioka, Hideo; Tabayashi, Kazuo; Izava, Yasuji, Journal of the Chemical Society. Chemical communications, 1985, # 13, p. 906 - 907