1451195-21-3Relevant articles and documents
Highly enantioselective Michael addition of pyrazolin-5-ones to nitroolefins catalyzed by cinchona alkaloid derived 4-methylbenzoylthioureas
Yang, Mengchen,Zhang, Min,Wang, Zhenyu,Tang, Li,Chen, Wenbin,Ban, Shurong,Li, Qingshan
supporting information, p. 1096 - 1104 (2018/08/11)
Cinchona alkaloid-derived 4-methyl/nitro benzoylthioureas were synthesized, which smoothly catalyzed the asymmetric Michael addition of pyrazolin-5-ones to nitroolefins. The results showed that electronic effects of substituents in the benzene ring of benzoylthioureas have subtle influences on their catalytic abilities and electron donating methyl group is favored than electron withdrawing nitro group. Preliminary Hartree-Fock calculations revealed that in the catalytic cycle, hydrogen bond energies of the complex formed with 4-methylbenzoylthioureas are about 0.19 to 1.56?kcal/mol higher than with the corresponding 4-nitrobenzoylthioureas. 4-Methylbenzoylthioureas were identified as the most effective catalysts that promoted asymmetric Michael addition of pyrazolin-5-ones to nitroolefins to give the S- or R-products with high enantioselectivities.
Squaramide-catalysed enantioselective Michael addition of pyrazolin-5-ones to nitroalkenes
Li, Jun-Hua,Du, Da-Ming
, p. 6215 - 6223 (2013/09/12)
An efficient chiral squaramide-catalysed enantioselective Michael addition of pyrazolin-5-ones to nitroalkenes has been developed. This reaction afforded the chiral pyrazol-3-ol derivatives in high to excellent yields (up to >99%) with high enantioselecti
