A New Lithium Alkoxide Accelerated Diastereoselective Cyanation of Ketones
作者:H. Scott Wilkinson、Paul T. Grover、Charles P. Vandenbossche、Roger P. Bakale、Nandkumar N. Bhongle、Stephen A. Wald、Chris H. Senanayake
DOI:10.1021/ol0069608
日期:2001.2.1
lithium heteroatom assisted TMSCN or TBSCN addition to aldehydes and ketones has been discovered. The process provides excellent selectivities and high rates. Conformationally constrained ketones such as camphor, fenchone, and nopinone give excellent diastereoselectivities with TMSCN. Reduction of 2 provided diastereopure amino alcohol 3 in good yield. alpha- and beta-Methyl cyclohexanones with TBSCN-LiOR
Calcined MgAICO<sub>3</sub>-HT Catalysed Cyanosilylation of Carbonyl Compounds and Nucleophilic Ring Opening of Oxiranes Using TMSCN
作者:B. M. Choudary、N. Narender、V. Bhuma
DOI:10.1080/00397919508011830
日期:1995.9
Nucleophilic addition of TMSCN to carbonyl compounds is found to be catalysed efficiently using hydrotalcite as a solid base. The catalyst is also found to be active in the nucleophilicringopening of oxiranes giving high regioselectivity.
Bacteriorhodopsin: The influence of the cyclohexene-ring methyls
作者:J. M. L. Courtin、L. Verhagen、P. L. Biesheuvel、J. Lugtenburg、R. L. van der Bend、K. van Dam
DOI:10.1002/recl.19871060402
日期:——
of the modified bacteriorhodopsins were much lower than those of the native system. UV-Vis and 1H NMR data support a planar 6-s-transconformation for the demethylated retinals in solution rather than a twisted 6-s-cis conformation (torsion angle 40-60°) as found in retinal. This explains the lower opsin shift and the better fit of these demethylated retinals in bacteriorhodopsin's binding site, which
四个环去甲基化视网膜,即。1,1,5'-tridemethylretinal,1,1'-didemethylretinal,1,5-didemethylretinal和1-didemethylretinal已通过新的简单方案合成。研究了这些修饰的视网膜,其质子化的席夫碱和相应的细菌视紫红质的特性,并将其与天然系统进行了比较。还对这些细菌视紫红质类似物的质子泵效率进行了测试。发现缺少5-甲基的类似物的质子泵活性大大降低。总体而言,修饰的细菌视紫红质的视蛋白移位远低于天然系统。UV-Vis和1 H NMR数据支持平面6 -s-trans溶液中去甲基化的视网膜的构象,而不是视网膜中扭曲的6 -s-顺式构象(扭转角40-60°)。这解释了视紫红质视蛋白移位较低,且这些去甲基化的视网膜更适合细菌视紫红质的结合位点,而细菌视紫红质的结合位点以其天然形式包含6 -s-反生色团。
Dodecatungestophosphoric acid (H3PW12O40) as a solid green BrØnsted acid catalyzes high yielding and efficient trimethylcyanosylilation reactions of aldehydes and ketones by trimethylsilyl cyanide
作者:Habib Firouzabadi、Nasser Iranpoor、Abbas Ali Jafari
DOI:10.1016/j.jorganchem.2004.12.025
日期:2005.3
An efficient solvent-free method is described for the addition of TMSCN to carbonyl groups employing dodecatungestophosphoric acid (H3PW12O40) as a heterogeneous and environmentally benign catalyst. By this method, aromatic, aliphatic, cyclic and heterocyclic aldehydes and ketones are converted into their corresponding cyanotrimethylsilyl ethers in excellent yields (89-98%) in short reaction times (< 10 min). (c) 2004 Published by Elsevier B.V.
Iodine as novel reagent for the 1,2-addition of trimethylsilyl cyanide to ketones including α,β-unsaturated ketones
Molecular iodine is found to catalyze efficiently the addition of trimethylsilyl cyanide to a range of simple and functionalized ketones under very mild and convenient conditions to afford the corresponding cyanohydrin trimethylsilyl ethers in excellent yields in a short reaction period with high selectivity. a,P-Unsaturated ketones selectively afford the corresponding 1,2-adducts without the formation of 1,4-adducts under similar reaction conditions. (C) 2002 Elsevier Science Ltd. All rights reserved.