Chiral iminophosphorane catalyzed asymmetric sulfenylation of 4-substituted pyrazolones
作者:Jianwei Han、Yanxia Zhang、Xin-Yan Wu、Henry N. C. Wong
DOI:10.1039/c8cc09049a
日期:——
An excellent level of enantioselectivity in asymmetric sulfenylation of 4-substituted pyrazolones was achieved with chiral iminophosphorane as the organocatalyst under continuum solvation conditions (up to 99% ee). Importantly, this catalytic process features high efficiency with excellent enantioselectivities, easy separation of products, low catalytic loadings and scale-up to grams without loss of
Highly Enantioselective Michael Addition of Pyrazolin-5-ones Catalyzed by Chiral Metal/N,N′-Dioxide Complexes: Metal-Directed Switch in Enantioselectivity
Make the switch: The first example of a switch in enantioselectivity in the asymmetric Michaeladdition of pyrazolin‐5‐ones to 4‐oxo‐4‐arylbutenoates that is controlled by the metal center of the catalyst is reported. By using the same N,N′‐dioxide ligand L with different metals the respective enantiomers of various 4‐substituted 5‐pyrazolone derivatives were obtained. Tf=trifluoromethanesulfonyl.
Diastereospecific Enantiodivergent Allylation of Pyrazolones as an Entry to β‐Aminoamides
作者:Nick Wannenmacher、Martin Heberle、Xin Yu、Aysegül Demircan、Daniel M. Wanner、Camilla Pfeffer、René Peters
DOI:10.1002/adsc.202200185
日期:2022.10.4
A diastereospecificenantiodivergentallylation of pyrazolones is reported which is catalyzed by a planar chiral pentaphenylferrocene based palladacycle. With the same catalyst batch both product enantiomers were selectively available. The method is applicable to structurally diverse substrates and gave products with enantiomeric excesses between 85 and 94%. In addition, we could show that pyrazolones
Highly selective: The title reaction is achieved with high enantiomeric and geometric control and thermodynamically unstable (Z)‐enone derivatives are obtained as the major products (see scheme). The procedure tolerates a wide range of substrates to generate optically active pyrazolones with vinyl‐substituted quaternary stereocenters.
A highly enantioselective regiodivergent addition of alkoxyallenes to pyrazolones was developed to afford multiply functionalized alkylated products bearing a quaternary carbon stereocenter in high yields with excellent stereoselectivities. One approach is enabled by palladiumcatalysis, thus leading to branched allylic pyrazol‐5‐ones under mild reaction conditions. The other is catalyzed by a chiral