Palladium-Catalyzed Stereoselective Hydrodefluorination of Tetrasubstituted <i>gem</i>-Difluoroalkenes
作者:Qiao Ma、Caroline Liu、Gavin Chit Tsui
DOI:10.1021/acs.orglett.0c01813
日期:2020.7.2
A highly stereoselective palladium(0)-catalyzed hydrodefluorination (HDF) of tetrasubstituted gem-difluoroalkenes is developed. By usingcatalytic Pd(PPh3)4 (2.5–5 mol %) and hydrosilane Me2PhSiH, various trisubstituted terminal (E)-monofluoroalkenes can be synthesized with excellent E/Z selectivity (>99:1) and good functional group tolerability. The key stereocontrol should be exerted by an ester-directed
A Catalytic Asymmetric Ring‐Expansion Reaction of Isatins and α‐Alkyl‐α‐Diazoesters: Highly Efficient Synthesis of Functionalized 2‐Quinolone Derivatives
Asymmetricexpansion: A catalyticasymmetricring‐expansionreaction of the title compounds occurs in the presence of a Sc(OTf)3 catalyst bearing an N,N′‐dioxide‐based ligand. Highlyfunctionalized2‐quinolonederivatives containing a chiral C4‐quaternary stereocenter were obtained in high yields and high levels of selectivity under mild reaction conditions (see scheme; Tf=trifluoromethanesulfonyl)
Palladium-Catalyzed Stereoselective C−F Bond Vinylation and Allylation of Tetrasubstituted <i>gem</i>-Difluoroalkenes via Stille Coupling: Synthesis of Monofluorinated 1,3- and 1,4-Dienes
作者:Min Li、Yanhui Wang、Gavin Chit Tsui
DOI:10.1021/acs.orglett.1c03096
日期:2021.10.15
We herein describe a Pd-catalyzed stereoselective C−F bond vinylation and allylation reaction of tetrasubstituted gem-difluoroalkenes for the synthesis of valuable monofluorinated 1,3- and 1,4-dienes with excellent diastereoselectivities. Different from previously used Pd(PPh3)4, a catalytic system involving Pd(0) and dppe as the ligand was developed for Stille-type cross-coupling between gem-difluoroalkenes
Highly Selective C–F Bond Functionalization of Tetrasubstituted <i>gem</i>-Difluoroalkenes and Trisubstituted Monofluoroalkenes Using Grignard Reagents
metal catalyst. β,β-Difluoroacrylates react with Grignard reagents under mild conditions to afford tetrasubstituted (E)-β-monofluoroacrylates. Experimental and computational studies revealed that the selectivity stems from the intrinsic reactivitydifference between the (E)- and (Z)-isomers toward excess Grignard reagent, which leads to the resolution of the two products.
我们在此描述了在没有过渡金属催化剂的情况下使用格氏试剂对四取代偕二氟烯烃和三取代单氟烯烃进行选择性 C-F 键官能化。β,β-二氟丙烯酸酯与格氏试剂在温和条件下反应生成四取代 ( E )-β-单氟丙烯酸酯。实验和计算研究表明,选择性源于 ( E )- 和 ( Z )-异构体对过量格氏试剂的内在反应性差异,这导致两种产物的分离。
Palladium-Catalyzed Stereoselective Defluorosilylation of <i>gem</i>-Difluoroalkenes for the Synthesis of Tetrasubstituted Monofluorinated Vinylsilanes
作者:Yuwei Zong、Ziwei Luo、Gavin Chit Tsui
DOI:10.1021/acs.orglett.3c00718
日期:——
Stereoselectivesynthesis of tetrasubstituted vinylsilanes is a challenging task. We herein report a novel palladium(0)-catalyzed defluorosilylation of β,β-difluoroacrylates to access tetrasubstituted vinylsilanes containing the monofluoroalkene motif in excellent diastereoselectivities (>99:1). This is our first example of C–heteroatom bond formation from the C–F bond under such a Pd catalytic manifold