Quinine-catalyzed enantioselective tandem conjugate addition/intramolecular cyclization of malononitrile and 1,4-dien-3-ones
作者:Zhi-Peng Hu、Jian Li、Xiao-Gang Yin、Xue-Jing Zhang、Ming Yan
DOI:10.3998/ark.5550190.0014.301
日期:——
An organocatalytic tandemconjugateaddition / intramolecularcyclization of malononitrile and conformationally restricted 1,4-dien-3-ones has been developed. A series of cinchona alkaloids and their derivatives were examined as the catalysts. Quinine was found to be the most efficient catalyst in the absence of any additive. The reaction gave 2-amino-4H-pyrans with high yield and excellent enantiopurity
1,3-Dipolar cycloadditions of nitrile sulphides to 1,4-quinones: a route to novel isothiazolonaphthoquinones and bis-(isothiazolo)benzoquinones
作者:R. Michael Paton、John F. Ross、John Crosby
DOI:10.1039/c39800001194
日期:——
Nitrilesulphides, generated by thermolysis of 1,3,4-oxathiazol-2-ones, react with 1,4-naphthoquinone and 1,4-benzoquinone to yield the isothiazoloquinones (4)–(6).