Asymmetric Imine Hydroboration Catalyzed by Chiral Diazaphospholenes
作者:Matt R. Adams、Chieh-Hung Tien、Robert McDonald、Alexander W. H. Speed
DOI:10.1002/anie.201709926
日期:2017.12.22
first use of diazaphospholenes as chiral catalysts has been demonstrated with enantioselective iminehydroboration. A chiral diazaphospholene prepared in a simple three‐step synthesis from commercial materials has been shown to achieve the highest enantioselectivity for the hydroboration of alkyl imines with pinacolborane reported to date. Enantiomer ratios of up to 88:12 were obtained with low (2 mol %)
Synthesis of 3,3-Disubstituted Oxindoles by Palladium-Catalyzed Asymmetric Intramolecular α-Arylation of Amides: Reaction Development and Mechanistic Studies
作者:Dmitry Katayev、Yi-Xia Jia、Akhilesh K. Sharma、Dipshikha Banerjee、Céline Besnard、Raghavan B. Sunoj、E. Peter Kündig
DOI:10.1002/chem.201301572
日期:2013.9.2
their performance is compared. One of them, L8, containing a tBu and a 1‐naphthyl group at the stereogenic centre, proved superior and was very efficient in the asymmetric synthesis of fifteen new spiro‐oxindoles and three azaspiro‐oxindoles often in high yields (up to 99 %) and enantioselectivities (up to 97 % ee; ee=enantiomeric excess). Three palladacycle intermediates resulting from the oxidative addition
掺有手性N-杂环卡宾(NHC)配体的钯配合物催化酰胺的不对称分子内α-芳基化反应,生成3,3-二取代的羟吲哚。已经进行了全面的DFT研究,以深入了解这种转变的机制。氧化添加被证明是决定速率的,还原消除是对映选择性的决定。详细介绍了七个新的NHC配体的合成,并比较了它们的性能。其中之一,L8,在立体异构中心含有一个t Bu和一个1-萘基,被证明是优越的,并且在不对称合成15个新的螺-氧杂吲哚和3个氮杂-螺氧杂吲哚中通常非常高的收率(高达99) %)和对映选择性(高达97% ee; ee =对映体过量)。分离并氧化了[Pd(NHC)]到芳基卤化物键中形成的三种palladacycle中间体,并对其结构进行了表征(X射线)。使用这些中间体作为催化剂,表明烯烃添加剂在增加周转次数和频率中起着重要的作用。
Chiral N-Heterocyclic Carbene Borane Complexes: Synthesis and Structural Analysis
作者:Dipshikha Banerjee、Céline Besnard、E. Peter Kündig
DOI:10.1021/om201087n
日期:2012.1.23
A new family of chiralN-heterocycliccarbene borane complexes was synthesized starting from their corresponding imidazoliumsalts. The complexes were fully characterized. X-ray crystal structures of the complexes were obtained.
Preparation of enantiomers of 1-(1-naphthyl)-2,2-dimethylpropylamine and their behaviour as chiral solvating agents: study of diastereochemic association by Job's plots and intermolecular NOE measurements
作者:A Port、A Virgili、A Alvarez-Larena、J.F Piniella
DOI:10.1016/s0957-4166(00)00334-7
日期:2000.9
Enantiomers of 1-(1-naphthyl)-2,2-dimethylpropylamine have been obtained and considered as chiral solvating agents against several compounds. The formed complexes have been studied with the aid of the nuclear Overhauser effect and its stoichiometry by the method of continuous variations. Two diastereoisomeric complexes present similar geometry of association by pi-pi -stacking of the aromatic rings and by hydrogen bonding of the functional groups. (C) 2000 Elsevier Science Ltd. All rights reserved.
Diaminophosphine Oxide Ligand Enabled Asymmetric Nickel-Catalyzed Hydrocarbamoylations of Alkenes
作者:Pavel A. Donets、Nicolai Cramer
DOI:10.1021/ja406730t
日期:2013.8.14
Chiral trivalent phosphorus species are the dominant class of ligands and the key controlling element in asymmetric homogeneous transition-metalcatalysis. Here, novel chiral diaminophosphine oxide ligands are described. The arising catalyst system with nickel(0) and trimethylaluminum efficiently activates formamide C-H bonds under mild conditions providing pyrrolidones via intramolecular hydrocarbamoylation