144883-03-4Relevant academic research and scientific papers
Broad Scope Synthesis of Ester Precursors of Nonfunctionalized Chiral Alcohols Based on the Asymmetric Hydrogenation of α,β-Dialkyl-, α,β-Diaryl-, and α-Alkyl-β-aryl-vinyl Esters
León, Félix,González-Liste, Pedro J.,García-Garrido, Sergio E.,Arribas, Inmaculada,Rubio, Miguel,Cadierno, Victorio,Pizzano, Antonio
, p. 5852 - 5867 (2017/06/07)
The catalytic asymmetric hydrogenation of trisubstituted enol esters using Rh catalysts bearing chiral phosphine-phosphite ligands (P-OP) has been studied. Substrates covered comprise α,β-dialkyl, α-alkyl-β-aryl, and α,β-diarylvinyl esters, the corresponding hydrogenation products being suitable precursors to prepare synthetically relevant chiral nonfunctionalized alcohols. A comparison of reactivity indicates that it decreases in the order: α,β-dialkyl > α-alkyl-β-aryl > α,β-diaryl. Based on the highly modular structure of P-OP ligands employed, catalyst screening identified highly enantioselective catalysts for α,β-dialkyl (95-99% ee) and nearly all of α-alkyl-β-aryl substrates (92-98% ee), with the exception of α-cyclohexyl-β-phenylvinyl acetate which exhibited a low enantioselectivity (47% ee). Finally, α,β-diarylvinyl substrates showed somewhat lower enantioselectivities (79-92% ee). In addition, some of the catalysts provided a high enantioselectivity in the hydrogenation of E/Z mixtures (ca. Z/E = 75:25) of α,β-dialkylvinyl substrates, while a dramatic decrease on enantioselectivity was observed in the case of α-methyl-β-anisylvinyl acetate (Z/E = 58:42). Complementary deuteration reactions are in accord with a highly enantioselective hydrogenation for both olefin isomers in the case of α,β-dialkylvinyl esters. In contrast, deuteration shows a complex behavior for α-methyl-β-anisylvinyl acetate derived from the participation of the E isomer in the reaction.
Electron-Transfer Photosensitized Oxygenation of Stilbene and Naphthalene Derivatives in the Presence of Acetate Ion. Controlling the Reaction of the Cation Radicals by Weak-Nucleophilic Salts
Yamashita, Toshiaki,Tsurusako, Taiji,Nakamura, Nobuya,Yasuda, Masahide,Shima, Kensuke
, p. 857 - 862 (2007/10/02)
The 9,10-Dicyanoanthracene (DCA)- or 9-cyanoanthracene-sensitized photooxygenation of trans-stilbene derivatives gave benzaldehyde derivatives efficiently in the presence of weak-nucleophilic salts, such as Et4NOAc and KOAc/18-crown-6 ether.The product distribution of this photooxygenation was apparently different from that of each photooxygenation in the presence of Mg(ClO4)2 and Et4NBF4 or in the absence of the salt.The DCA-sensitized photooxygenation of 2-methylnaphthalene gave phthalic acid and 4-methylphthalic acid in the presence of Nt4NOAc.These products were different from the products generated from each photooxygenation in the presence of Et4NBF4 and KClO4 or in the absence of the salt.Also, such ring-oxygenation occurred in the DCA-sensitized photooxygenation of 2,3-dimethylnaphthalene and naphthalene in the presence of Et4NOAc.These photooxygenations in the presence of Et4NOAc proceeded by the addition of an acetate ion to the cation radical of the substrate generated by a photochemical electron transfer from the substrate to the sensitizer and the subsequent reaction with O2 and the related oxygen species.
The Palladium-Catalyzed Cross-Coupling Reaction of Enol Acetates of α-Bromo Ketones with 1-Alkenyl-, Aryl-, or Alkylboron Compounds; A Facile Synthesis of Ketones and Their Enol Acetates
Abe, Shigeru,Miyaura, Norio,Suzuki, Akira
, p. 2863 - 2865 (2007/10/02)
The synthesis of stereodefined enol acetates of ketones is readily accomplished by palladium-catalyzed cross-coupling reaction between alkyl-, aryl-, or 1-alkenylboron reagents with enol acetates of α-bromo ketones.Hydroboration of alkene with 9-BBN, followed by coupling with (Z)-2-ethoxy-1-bromoethene gives the enol ether of aldehyde.These enol acetates and ethers are readily deprotected to give corresponding ketones and aldehydes in high yields.
