198625-67-1Relevant articles and documents
Development of Chiral Organosuperbase Catalysts Consisting of Two Different Organobase Functionalities
Kondoh, Azusa,Oishi, Masafumi,Terada, Masahiro,Tezuka, Hikaru
, p. 7472 - 7477 (2020/03/19)
In the field of chiral Br?nsted base catalysis, a new generation of chiral catalysts has been highly anticipated to overcome the intrinsic limitation of pronucleophiles that are applicable to the enantioselective reactions. Herein, we reveal conceptually new chiral Br?nsted base catalysts consisting of two different organobase functionalities, one of which functions as an organosuperbase and the other as the substrate recognition site. Their prominent activity, which stems from the distinctive cooperative function by the two organobases in a single catalyst molecule, was demonstrated in the unprecedented enantioselective direct Mannich-type reaction of α-phenylthioacetate as a less acidic pronucleophile. The present achievement would provide a new guiding principle for the design and development of chiral Br?nsted base catalysts and significantly broaden the utility of Br?nsted base catalysis in asymmetric organic synthesis.
Catalytic performance of polystyrene-bound ChibaG derivatives as guanidine organobases in asymmetric Michael additions
Ishikawa, Tsutomu,Heima, Takashi,Yoshida, Makoto,Kumamoto, Takuya
, p. 307 - 314 (2014/04/03)
The guanidine organocatalyst, ChibaG, was bound via an ether linkage to the phenyl group of the 2-imino substituent to Merrifield resin. Polystyrene-bound ChibaG acted as an effective catalyst in the Michael reaction of tert-butyl N-(diphenylmethylidene)g
Pentanidium-catalyzed enantioselective α-hydroxylation of oxindoles using molecular oxygen
Yang, Yuanyong,Moinodeen, Farhana,Chin, Willy,Ma, Ting,Jiang, Zhiyong,Tan, Choon-Hong
supporting information, p. 4762 - 4765 (2013/01/15)
Pentanidium-catalyzed α-hydroxylation of 3-substituted-2-oxindoles using molecular oxygen has been developed with good yields and enantioselectivities. This reaction does not require an additional reductant such as triethyl phosphite, which was typically added to reduce the peroxide intermediate. The reaction was demonstrated to consist of two-steps: an enantioselective formation of hydroperoxide oxindole and a kinetic resolution of the hydroperoxide oxindole via reduction with enolates generated from the oxindoles.