The asymmetriccopper-catalyzedconjugateaddition to α-alkylidene cycloalkanones, substituted at their terminal position with aromatic and aliphatic groups, is reported. While high enantioselectivity is reached using chiral phosphoramidite ligands, with R3Al reagents, moderate diastereoselectivity was observed upon hydrolysis of the aluminium enolates. A Grignard reagent also react with high diastereoselectivity
A RuPHOX-Ru catalyzed selective asymmetrichydrogenation of exocyclic α,β-unsaturated ketones has been developed, furnishing the corresponding chiral exocyclic allylic alcohols in high yields and with up to >99.5% ee. The reaction could be performed on a gram scale with a relatively low catalyst loading (up to 10000 S/C) without any loss in reaction activity and enantioselectivity. The resulting hydrogenated
已开发出RuPHOX-Ru催化的环外α,β-不饱和酮的选择性不对称氢化,可提供高收率和最高> 99.5%ee的相应手性环外烯丙基醇。该反应可以以克级进行,具有相对较低的催化剂负载量(最高10000 S / C),而没有任何反应活性和对映选择性的损失。所得的氢化产物可以容易地转化为具有高不对称性能的几种生物活性化合物。不对称方案为合成手性环外烯丙基醇提供了一种有效的方法。
Chiral diphosphorus compounds and transition metal complexes thereof
申请人:Knochel Paul
公开号:US20050288523A1
公开(公告)日:2005-12-29
The present invention relates to chiral diphosphorus compounds and transition metal complexes thereof, to a process for preparing chiral diphosphorus compounds and oxides thereof, and transition metal complexes comprising the chiral diphosphorus compounds. In a further aspect, the invention relates to the use of the chiral diphosphorus compounds or transition metal complexes thereof in asymmetric syntheses.
Asymmetric reduction of prochiral cycloalkenones. The influence of exocyclic alkene geometry
作者:Alison F. Simpson、Corinna D. Bodkin、Craig P. Butts、Mark A. Armitage、Timothy Gallagher
DOI:10.1039/b004540n
日期:——
The asymmetric reduction of a series of prochiral enones of general structure 1 using the Corey oxazaborolidine 2, leading to enantiomerically enriched allylic cycloalkanols 3 is described. The influence of alkene geometry on both the sense (Rvs. S) and efficiency (% ee) of the asymmetric reduction process has been probed for two systems, (E)- and (Z)-4 and (E)- and (Z)-7, based on cyclohexanone and cyclopentanone respectively. The absolute stereochemistry of the cyclopentyl derivative (E)-8 has been established by X-ray crystallographic analysis of carbamate 10. The ability to assign an absolute configuration to allylic alcohols 3, based on the NMR methods described earlier by Riguera, has been evaluated.
Acid Catalyzed Rearrangements of Conjugated Cyclopropyl and Epoxy Ketones
作者:E. Lee-Ruff、P. Khazanie
DOI:10.1139/v75-242
日期:1975.6.15
A series of spiro[n.2]alkan-2-ones and their 6 and 7 oxa derivatives were subjected to acid catalysis. In the former series, products arising from hydroxyl(cyclopropyl)carbinyl cations are observed...