0000000000018304
AUTHOR
Fares Ibrahim Amr
Organocatalytic Enantioselective Synthesis of Pyrazoles Bearing a Quaternary Stereocenter
An efficient one-pot asymmetric synthesis of pyrazoles bearing a chiral quaternary stereocenter has been developed. Quinine-derived thiourea catalyzed the enantioselective addition of pyrazolones to isatin-derived ketimines, providing the corresponding acetylated pyrazoles after in situ treatment with Ac2O/Et3N. The corresponding pyrazoles were afforded in high yields and excellent enantioselectivities.
ChemInform Abstract: Organocatalytic Enantioselective Alkylation of Pyrazol-3-ones with Isatin-Derived Ketimines: Stereocontrolled Construction of Vicinal Tetrasubstituted Stereocenters.
Financial support from the MINECO (Gobierno de Espana and FEDER (EU)) (CTQ2013-47949-P) and from Generalitat Valenciana (ISIC2012/001) is gratefully acknowledged. C. V. thanks MINECO for JdC contract. Access to NMR, MS and X-ray facilities from the Servei central de support a la investigacio experimental (SCSIE)-UV is also acknowledged.
ChemInform Abstract: Organocatalytic Enantioselective Synthesis of Pyrazoles Bearing a Quaternary Stereocenter.
An efficient one-pot asymmetric synthesis of pyrazoles bearing a chiral quaternary stereocenter has been developed. Quinine-derived thiourea catalyzed the enantioselective addition of pyrazolones to isatin-derived ketimines, providing the corresponding acetylated pyrazoles after in situ treatment with Ac2 O/Et3 N. The corresponding pyrazoles were afforded in high yields and excellent enantioselectivities.
Organocatalytic Enantioselective Alkylation of Pyrazol-3-ones with Isatin-Derived Ketimines: Stereocontrolled Construction of Vicinal Tetrasubstituted Stereocenters
A quinine-derived thiourea catalysed the enantioselective addition of 4-substituted pyrazolones to isatin-derived ketimines, providing a variety of aminooxindole-pyrazolone adducts containing congested vicinal tetrasubstituted stereocentres with excellent outcomes (up to 98% yield, >20:1 dr and 98% ee).
CCDC 1444032: Experimental Crystal Structure Determination
Related Article: Fares Ibrahim Amr, Carlos Vila, Gonzalo Blay, M. Carmen Muñoz and José R. Pedro|2016|Adv.Synth.Catal.|358|1583|doi:10.1002/adsc.201600036
CCDC 1463856: Experimental Crystal Structure Determination
Related Article: Carlos Vila, Fares Ibrahim Amr, Gonzalo Blay, M. Carmen Munoz, Jose R. Pedro|2016|Chem.Asian J.|11|1532|doi:10.1002/asia.201600325