78024-77-8Relevant academic research and scientific papers
Enantioselective Desymmetrization of 2-Aryl-1,3-propanediols by Direct O-Alkylation with a Rationally Designed Chiral Hemiboronic Acid Catalyst That Mitigates Substrate Conformational Poisoning
Estrada, Carl D.,Ang, Hwee Ting,Vetter, Kim-Marie,Ponich, Ashley A.,Hall, Dennis G.
, (2021/04/07)
Enantioselective desymmetrization by direct monofunctionalization of prochiral diols is a powerful strategy to prepare valuable synthetic intermediates in high optical purity. Boron acids can activate diols toward nucleophilic additions; however, the design of stable chiral catalysts remains a challenge and highlights the need to identify new chemotypes for this purpose. Herein, the discovery and optimization of a bench-stable chiral 9-hydroxy-9,10-boroxarophenanthrene catalyst is described and applied in the highly enantioselective desymmetrization of 2-aryl-1,3-diols using benzylic electrophiles under operationally simple, ambient conditions. Nucleophilic activation and discrimination of the enantiotopic hydroxy groups on the diol substrate occurs via a defined chairlike six-membered anionic complex with the hemiboronic heterocycle. The optimal binaphthyl-based catalyst 1g features a large aryloxytrityl group to effectively shield one of the two prochiral hydroxy groups on the diol complex, whereas a strategically placed "methyl blocker"on the boroxarophenanthrene unit mitigates the deleterious effect of a competing conformation of the complexed diol that compromised the overall efficiency of the desymmetrization process. This methodology affords monoalkylated products in enantiomeric ratios equal or over 95:5 for a wide range of 1,3-propanediols with various 2-aryl/heteroaryl groups.
Customized Buchwald-Type Phosphines Bearing an "Inverted" Pyrimidinium Betaine as an Aryl Group Surrogate - Synthesis and Coordination Chemistry with Gold(I)
No?l-Duchesneau, Ludovik,Lugan, No?l,Lavigne, Guy,Labande, Agnès,César, Vincent
, p. 1752 - 1758 (2015/04/14)
A new ligand scaffold inspired by Buchwald-type phosphines is disclosed. Its design consists of the formal replacement of the distal aryl group of the original archetype by a pyrimidinium betaine connected to the o-phosphinophenyl moiety through the C-5 position of its malonate subunit. A productive synthetic pathway towards this phosphine is described along with its ability to coordinate to a gold(I) center. A weak bonding interaction between the metal center and the malonate group is observed in the solid state.
Synthesis of indenes by the palladium-catalyzed carboannulation of internal alkynes
Zhang, Daohua,Eul, Kgun Yum,Liu, Zhijian,Larock, Richard C.
, p. 4963 - 4966 (2007/10/03)
(Chemical Equation Presented) A number of highly substituted indenes have been prepared in good yields by treating functionally substituted aryl halides with various internal alkynes in the presence of a palladium catalyst. The reaction is believed to proceed by regioselective arylpalladation of the alkyne and subsequent nucleophilic displacement of the palladium in the resulting vinylpalladium intermediate.
COPPER(I)-PROMOTED COUPLING REACTION OF ARYL HALIDES WITH SODIUM DIETHYLMALONATE
Setsune, Jun-ichiro,Matsukawa, Kimihiro,Wakemoto, Hirofumi,Kitao, Teijiro
, p. 367 - 370 (2007/10/02)
Copper(I)-promoted coupling reaction of aryl halides with sodium diethylmalonate occured smoothly in dioxane.The qualitative trends in the activity of copper(I) salt followed the order: CuBr > CuI > CuBF4(CH3CN)4 > CuCl.The activity was lowered in the presence of coordinating molecule such as acetonitrile, pyridine, NaI, phosphine, and sulfide.The reaction was generally applicable to aryl halides with various substituents.
