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Sun J.,Institute and State Key Laboratory of Elemento Organic Chemistry | Sun J.,Nankai University | Jiang C.,Institute and State Key Laboratory of Elemento Organic Chemistry | Jiang C.,Nankai University | And 2 more authors.
European Journal of Organic Chemistry | Year: 2016

The application of readily available optically active 4-substituted 5-nitropentan-2-ones as chiral building blocks in the stereocontrolled construction of spiro-pyrazolone scaffolds was investigated. In the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (1 equiv.) optically active 4-substituted 5-nitropentan-4-ones exhibited excellent chiral inducing abilities in the diastereoselective cascade Michael/aldol reaction with a wide range of unsaturated pyrazolones to generate the corresponding biologically significant spiro-pyrazolone derivatives with five contiguous stereocenters in acceptable to good yield with high levels of diastereoselectivity. Optically active 4-substituted 5-nitropentan-2-ones proved valuable chiral building blocks in the stereocontrolled construction of spiro-pyrazolone scaffolds. A range of spiro-pyrazolones were synthesized in good yields with high levels of diastereo- and enantioselectivity through a base-mediated cascade Michael/aldol reaction between 4-substituted 5-nitropentan-2-ones and unsaturated pyrazolones. © Copyright 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Cui L.-Y.,Institute and State Key Laboratory of Elemento Organic Chemistry | Cui L.-Y.,Nankai University | Wang Y.-H.,Institute and State Key Laboratory of Elemento Organic Chemistry | Wang Y.-H.,Nankai University | And 6 more authors.
RSC Advances | Year: 2015

An efficient approach for the stereocontrolled construction of 3H-furo[3,4-b]chromen-1(9H)-one skeleton has been successfully developed through a sequential Michael addition/intramolecular dehydration strategy. The Michael addition of tetronic acid to 2-((E)-2-nitrovinyl)phenols catalyzed by a bifunctional squaramide derived from l-tert-leucine, and the subsequent intramolecular dehydration promoted by concentrated sulfuric acid, proceed smoothly to give the corresponding pharmaceutically valuable 3H-furo[3,4-b]chromen-1(9H)-ones in acceptable yields with 79-97% ee. © The Royal Society of Chemistry.

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