Highly Selective Cascade Couplings for the Syntheses of Functionalized Piperidinones and Bispidines
摘要:
Efficient cascade couplings to synthesize functionalized piperidinones 1 and bispidines 2 and 3 have been developed. Simple modifications to the reaction conditions allow for the highly controlled and selective formation of each compound. In addition, the cis isomer of 1 can be selectively obtained under acidic conditions, while the preparation of the corresponding trans isomer can also be readily realized through a base-catalyzed, dynamic crystallization-driven process.
A series of novel carbohydrate-derived thioureas were synthesized and examined as catalysts for the asymmetric Michael addition of symmetrical 1,3-dicarbonyl compounds, including dimethyl malonate, to several trans-β-nitrostyrenes. High enantioselectivities (up to 94% ee) as well as high yields (up to 98%) were attained using a bifunctional organocatalyst bearing a cinchona-based alkaloid unit.
Bis(imidazolidine)pyridine‐CoCl
<sub>2</sub>
: A Novel, Catalytically Active Neutral Complex for Asymmetric Michael Reaction of 1,3‐Carbonyl Compounds with Nitroalkenes
作者:Takayoshi Arai、Yuko Iimori、Mayu Shirasugi、Ryota Shinohara、Yuri Takagi、Takumi Suzuki、Junma Ma、Satoru Kuwano、Hyuma Masu
DOI:10.1002/adsc.201900421
日期:2019.8.21
A neutral bis(imidazolidine)pyridine (PyBidine)‐CoCl2 complex showed catalytic activity for the Michael reaction of malonates with nitroalkenes. The results indicated that a weak amine base aided enolate formation from the neutral complex, in which the N−H proton of the imidazolidine ligand played a significant role.
作者:Lei Zhang、Myoung-Mo Lee、Soo-Mi Lee、Jihye Lee、Maosheng Cheng、Byeong-Seon Jeong、Hyeung-geun Park、Sang-sup Jew
DOI:10.1002/adsc.200900787
日期:2009.12
e with C(9S)-aminodihydroquinine or C(9R)-aminodihydroquinidine and successively applied to the Michael addition of dimethyl malonate to nitroolefins as very efficient chiral Lewis acid bifunctionalorganocatalysts (up to >99% ee).
Mimicking Enzymes: Asymmetric Induction inside a Carbamate–Based Steroidal Cleft
作者:Carmen Concellón、Judith Martín、Miguel Gallegos、Noé Fanjul-Mosteirín、Aurora Costales、Ángel Martín Pendás、Vicente del Amo
DOI:10.1021/acs.orglett.9b01170
日期:2019.6.7
Cholic acid has been elaborated into a carbamate-based tripodal architecture, which is able to promote an asymmetric organic transformation inside its chiral cavity. The nature of this steroidal catalyst has been disclosed by quantum-chemical calculations. It comprises the preorganization and confinement of the reagents within the cavity of the steroid to form a supramolecular complex held together
Cinchona alkaloid-based chiral catalysts act as highly efficient multifunctional organocatalysts for the asymmetric conjugate addition of malonates to nitroolefins
作者:Veeramanoharan Ashokkumar、Ayyanar Siva
DOI:10.1039/c5ob01351h
日期:——
quaternary ammonium salts acting as organocatalysts (7a and 7b) have been prepared and used as organocatalysts for enantioselective Michael addition reactions between various nitroolefins and Michael donors (malonates) under mild reaction conditions, such as lower concentration of base and catalyst and room temperature, with very good chemical yields (up to 97%) and ee's (up to 99%).