A novel annulation reaction of two enamine molecules with iodine under basic conditions to form 4-functionalized imidazolium salts has been established. In this reaction, iodine acts as both an iodinating reagent and a Lewis acid catalyst. Features of this synthetic method include facilitative preparation of substrates, no use of transition metals, mild reaction conditions, simplicity of operation
The annulation of N-cyclopropyl enamines to produce 1,4-dihydropyridine (1,4-DHP) derivatives is described. In the presence of molecular iodine (I2), an N-cyclopropyl enamine substrate undergoes iodination, opening of the cyclopropyl ring, and annulation with a second molecule of the substrate to form the 1,4-DHP product. This reaction is amenable to gram-scale operations under mild reaction conditions
Mechanochemical electrophilic fluorination of liquid beta-ketoesters
作者:Joseph L. Howard、Yerbol Sagatov、Duncan L. Browne
DOI:10.1016/j.tet.2017.11.066
日期:2018.6
An improved substrate scope for the mechanochemical electrophilicfluorination of dicarbonyls is reported. The applicable substrates have now been broadened to include liquid β-ketoesters. Key to this capability is the inclusion of a grinding auxiliary (NaCl) to improve mass transfer and prevent pasting or gumming of the reaction mixture. Notably, the use of a small amount of acetonitrile is critical
Chiral Lewis Base-Catalyzed, Enantioselective Reduction of Unprotected β-Enamino Esters with Trichlorosilane
作者:Jianheng Ye、Chao Wang、Lin Chen、Xinjun Wu、Li Zhou、Jian Sun
DOI:10.1002/adsc.201501061
日期:2016.3.31
reduction of N‐unsubstituted β‐enamino esters represents a major challenge for asymmetric catalysis. In this paper, the first organocatalytic system that could be used for the asymmetric hydrosilylation of N‐unsubstituted β‐enamino esters has been developed. Using N‐tert‐butylsulfinyl‐L‐proline‐derived amides and L‐pipecolinic acid‐derived formamides as catalyst, a broad range of β‐aryl‐ and β‐alkyl‐substituted
Vicinal tricarbonyl intermediates are directly synthesized from β-dicarbonyls with the aid of Cu(II) salts and air, and they are further condensed with phenylene diamine to produce a range of quinoxalines in moderate to good yields in one-pot reaction.