29841-69-8Relevant articles and documents
Optical resolution of racemic stilbenediamine using N*-chiral ortho-palladated matrix
Dunina,Kuz'mina,Parfyonov,Griskin
, p. 183 - 194 (1999)
Optical resolution of racemic stilbenediamine (Stien) was performed by recrystallization of its diastereomeric adducts with ortho-palladated (S)-N-isopropyl-α-methylbenzylamine. The less soluble (SCRN,SS) diasteteomer was studied by X-ray diffraction analysis. It was established that the crystal of this diastereomer consists of dimers formed via association of two molecules of the mononuclear cationic complex with an additional molecule of free diamine of the same absolute configuration. The association occurs through a system of hydrogen bonds and weak agostic interactions. Based on the X-ray diffraction data, the procedure was improved for the resolution of stilbenediamine due to the more profitable use of the ortho-palladated reagent. The Stien/Pd ratio in the diastereomer isolated was increased up to 3 : 2. The conformational features of the complex are discussed on the basis of 1H NMR spectroscopy data.
Improved Optical Resolution of (+/-)-1,2-Diphenylethylenediamine
Saigo, Kazuhiko,Kubota, Naomi,Takebayashi, Shoko,Hasegawa, Masaki
, p. 931 - 932 (1986)
(+/-)-1,2-Diphenylethylenediamine (DPEDA) was efficiently resolved by the fractional crystallization of its diastereomeric salts with optically active mandelic acid. 1H-NMR spectrum of N-monoacylated DPEDA with an optically active derivatizing agent showed that DPEDA thus obtained was optically pure.
Mechanistic studies inform design of improved Ti(salen) catalysts for enantioselective [3 + 2] cycloaddition
Robinson, Sophia G.,Wu, Xiangyu,Jiang, Binyang,Sigman, Matthew S.,Lin, Song
, p. 18471 - 18482 (2020/11/17)
Ti(salen) complexes catalyze the asymmetric [3 + 2] cycloaddition of cyclopropyl ketones with alkenes. While high enantioselectivities are achieved with electron-rich alkenes, electron-deficient alkenes are less selective. Herein, we describe mechanistic studies to understand the origins of catalyst and substrate trends in an effort to identify a more general catalyst. Density functional theory (DFT) calculations of the selectivity determining transition state revealed the origin of stereochemical control to be catalyst distortion, which is largely influenced by the chiral backbone and adamantyl groups on the salicylaldehyde moieties. While substitution of the adamantyl groups was detrimental to the enantioselectivity, mechanistic information guided the development of a set of eight new Ti(salen) catalysts with modified diamine backbones. These catalysts were evaluated with four electron-deficient alkenes to develop a three-parameter statistical model relating enantioselectivity to physical organic parameters. This statistical model is capable of quantitative prediction of enantioselectivity with structurally diverse alkenes. These mechanistic insights assisted the discovery of a new Ti(salen) catalyst, which substantially expanded the reaction scope and significantly improved the enantioselectivity of synthetically interesting building blocks.
Enantioselective Reductive Coupling of Imines Templated by Chiral Diboron
Chen, Dongping,Li, Kaidi,Tang, Wenjun,Xu, Guangqing,Xu, Ronghua,Zhou, Mingkang
supporting information, p. 10337 - 10342 (2020/07/04)
We herein report a general, practical, and highly efficient method for asymmetric synthesis of a wide range of chiral vicinal diamines via reductive coupling of imines templated by chiral diboron. The protocol features high enantioselectivity and stereospecificity, mild reaction conditions, simple operating procedures, use of readily available starting materials, and a broad substrate scope. The method signifies the generality of diboron-enabled [3,3]-sigmatropic rearrangement.
Synergistic copper-TEMPO catalysis of intermolecular vicinal diamination of styrenes
Weng, Shiue-Shien,Hsieh, Kun-Yi,Zeng, Zih-Jian,Zhang, Jia-Wei
, p. 670 - 673 (2017/01/25)
A copper-catalyzed, 2,2,6,6-tetramethyl piperidine N-oxy radical-assisted intermolecular diamination of styrenes with N-fluorobenzenesulfonimide has been developed. The current protocol proved amenable to a diverse array of styrenes via cascade radical addition to readily afford synthetically useful aromatic vicinal diamines with exclusive diastereoselectivity.