79825-70-0Relevant articles and documents
Difluoroisoxazolacetophenone: A Difluoroalkylation Reagent for Organocatalytic Vinylogous Nitroaldol Reactions of 1,2-Diketones
Zhang, Yong,Ge, Jin,Luo, Liang,Yan, Su-Qiong,Lai, Guo-Wei,Mei, Zu-Qin,Luo, Hai-Qing,Fan, Xiao-Lin
supporting information, p. 7952 - 7957 (2020/11/02)
Difluoroisoxazolacetophenone (DFIO) is developed as a new difluoroalkylation reagent that can be easily prepared from inexpensive starting materials. In situ remote C-C bond cleavage of DFIO affords γ,γ-difluoroisoxazole nitronate that undergoes base-catalyzed vinylogous nitroaldol additions to isatins, benzothiophene-2,3-dione, unsaturated-α-ketoesters, and cyclic 1,2-diketones. This organocatalytic debenzoate vinylogous nitroaldol reaction provides a new and mild approach for the preparation of various difluoroisoxazole-substituted 3-hydroxy-2-oxindoles.
Dehydrogenative Coupling of Aldehydes with Alcohols Catalyzed by a Nickel Hydride Complex
Eberhardt, Nathan A.,Wellala, Nadeesha P. N.,Li, Yingze,Krause, Jeanette A.,Guan, Hairong
, p. 1468 - 1478 (2019/04/17)
A nickel hydride complex, {2,6-(iPr2PO)2C6H3}NiH, has been shown to catalyze the coupling of RCHO and R′OH to yield RCO2R′ and RCH2OH, where the aldehyde also acts as a hydrogen acceptor and the alcohol also serves as the solvent. Functional groups tolerated by this catalytic system include CF3, NO2, Cl, Br, NHCOMe, and NMe2, whereas phenol-containing compounds are not viable substrates or solvents. The dehydrogenative coupling reaction can alternatively be catalyzed by an air-stable nickel chloride complex, {2,6-(iPr2PO)2C6H3}NiCl, in conjunction with NaOMe. Acids in unpurified aldehydes react with the hydride to form nickel carboxylate complexes, which are catalytically inactive. Water, if present in a significant quantity, decreases the catalytic efficiency by forming {2,6-(iPr2PO)2C6H3}NiOH, which causes catalyst degradation. On the other hand, in the presence of a drying agent, {2,6-(iPr2PO)2C6H3}NiOH generated in situ from {2,6-(iPr2PO)2C6H3}NiCl and NaOH can be converted to an alkoxide species, becoming catalytically competent. The proposed catalytic mechanism features aldehyde insertion into the nickel hydride as well as into a nickel alkoxide intermediate, both of which have been experimentally observed. Several mechanistically relevant nickel species including {2,6-(iPr2PO)2C6H3}NiOC(O)Ph, {2,6-(iPr2PO)2C6H3}NiOPh, and {2,6-(iPr2PO)2C6H3}NiOPh·HOPh have been independently synthesized, crystallographically characterized, and tested for the catalytic reaction. While phenol-containing molecules cannot be used as substrates or solvents, both {2,6-(iPr2PO)2C6H3}NiOPh and {2,6-(iPr2PO)2C6H3}NiOPh·HOPh are efficient in catalyzing the dehydrogenative coupling of PhCHO with EtOH.
Efficient and selective palladium-catalyzed direct oxidative esterification of benzylic alcohols under aerobic conditions
Hu, Yongke,Li, Bindong
, p. 7301 - 7307 (2017/11/29)
A highly efficient palladium-catalyzed approach for the direct oxidative esterification of benzylic alcohols with methanol and long-chain aliphatic alcohols under mild conditions has been achieved. This practical catalyst system exhibits a broad substrate scope and good functional group tolerance. Catalytic amount of Bi(OTf)3 is used as co-catalyst to improve the activity and selectivity of the reactions. A variety of esters are obtained in yields of 43–96%.
