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 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
Enantioselective Direct α-Arylation of Pyrazol-5-ones with 2-Indolylmethanols via Organo-Metal Cooperative Catalysis
作者:Zi-Qi Zhu、Yang Shen、Jin-Xi Liu、Ji-Yu Tao、Feng Shi
DOI:10.1021/acs.orglett.7b00351
日期:2017.4.7
The first catalytic asymmetric α-arylation of pyrazol-5-ones has been established by using 2-indolylmethanols as direct electrophilicarylation reagents under the cooperative catalysis of Pd(0) and a chiral phosphoric acid, which afforded the α-arylation products of pyrazol-5-ones in generally high yields and good enantioselectivities (up to 99% yield, >99% ee).