Palladium-Catalyzed Intramolecular Hydroalkylation of Alkenyl- ?-Keto Esters, ?-Aryl Ketones, and Alkyl Ketones in the Presence of Me3SiCl or HCl
作者:Xiaoqing Han、Xiang Wang、Tao Pei、Ross A. Widenhoefer
DOI:10.1002/chem.200400459
日期:2004.12.17
palladium-catalyzed hydroalkylation, but rather served as a source of HCl, which presumably catalyzes enolization of the ketone. Identification of HCl as the active promoter of palladium-catalyzed hydroalkylation led to the development of an effective protocol for the hydroalkylation of alkyl 3-butenyl ketones that employed sub-stoichiometric amounts of 2, HCl, and CuCl2 in a sealed tube at 70 degrees C.
Enantioselective Total Synthesis of (R)-α-Lipoic Acid: An Application of Thermodynamically Controlled Deracemization of (±)-2-(2-Methoxyethyl)cyclohexanone
According to the concept of thermodynamically controlled deracemization, racemic 2-(2-methoxyethyl)cyclohexanone was converted into the R-isomer (99% ee) in 90% yield using (-)-(2R,3R)-trans-2,3-bis(hydroxydiphenylmethyl)-1,4-dioxaspiro[5.4]decane as a host molecule under basic conditions. As an application, a short and enantioselective synthesis of (R)-α-lipoic acid was accomplished in 44% overall
Alkoxyalkyl Spirocyclic Tetramic Acids and Tetronic Acids
申请人:Fischer Reiner
公开号:US20090215624A1
公开(公告)日:2009-08-27
The invention relates to novel alkoxyalkyl spirocyclic tetramic and tetronic acids of the formula (I),
in which
A, B, D, Q
1
, Q
2
, Q
3
, Q
4
, G, W, X, Y and Z are as defined above,
to a plurality of processes and intermediates for their preparation and to their use as pesticides and/or herbicides and/or microbicides, and also to selective herbicidal compositions comprising, firstly, the alkoxyalkyl spirocyclic tetramic and tetronic acids and, secondly, at least one crop plant compatibility-improving compound.
efficiency of this thermodynamically controlled deracemization was strongly influenced by the mixture ratio of the solvent, H2O/MeOH. Based on this finding, an improved method of preparing (R)-2-monosubstituted cycloalkanones with higher optical purity was developed. For example, (R)-2-(4-methylbenzyl)cyclohexanone (5) was obtained in 85% yield with 98% ee, when a 1:1 mixture of H2O/MeOH was used as the solvent
当在碱性MeOH水溶液中将TADDOLs(例如1a,b)用作主体分子时,外消旋的2-单取代的环烷酮被转化为R-异构体。该热力学控制的脱硝的效率受到溶剂H 2 O / MeOH的混合比的强烈影响。基于该发现,开发了制备具有更高光学纯度的(R)-2-单取代的环烷酮的改进方法。例如,(- [R)-2-(4-甲基苄基)环己酮(5以85%的产率得到98%ee的,当1):H 1混合物2中使用O / MeOH作为溶剂中的存在1a。
Deracemization of 2-alkylcyclohexanones utilizing host-guest molecular association with optically active host compounds in basic suspension media
Based on host-guest inclusion complexation in the solid state, α-substituted cyclohexanones 2a-c were deracemized using optically active host compounds in alkaline conditions to optically active 2 in excellent chemical yield with high enantiomeric excess.