94112-78-4Relevant articles and documents
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.
Mesoionic Compound
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Paragraph 0350; 0351, (2018/11/21)
The purpose of the present invention is to provide a mesoionic compound or a salt thereof that exhibits excellent control activity against various pests. Provided is a mesoionic compound represented by formula (1). (In the formula, Ra represents a hydrogen atom or a methyl group, R1 represents a phenyl group or pyridyl group which is optionally substituted with up to two substituents selected independently from R2, and R2 represents a hydrogen atom, a fluorine atom, a chlorine atom, a bromine atom, a methyl group, an ethyl group, an n-propyl group, an i-propyl group, a c-propyl group, an n-butyl group, an i-butyl group, an s-butyl group, a t-butyl group, a fluoromethyl group, a difluoromethyl group, a trifluoromethyl group, a methyloxy group, an ethyloxy group, an n-propyloxy group, an i-propyloxy group, a c-propyloxy group, an n-butyloxy group, an i-butyloxy group, a s-butyloxy group, a t-butyloxy group, an n-pentyloxy group, a trifluoromethyloxy group, a 2,2,2-trifluoroethyloxy group, a methylthio group, a methylsulfoxy group, a methylsulfonyl group, a vinyl group, an ethynyl group, etc.)
New efficient ligand-free, copper nanoparticle catalyzed coupling reactions of aryl halides with diethyl malonate to produce α-arylation of malonates
Pai, Gita,Chattopadhyay, Asoke P.
, p. 1475 - 1482 (2013/06/27)
Recently synthesized copper nanoparticles (Cu NP) were used to catalyze coupling of aryl halides with diethyl malonates to produce α-aryl malonates. Synthetic conditions, including solvents, relative amounts of reactants, catalyst, and temperature, etc. h
