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
Visible-Light-Induced Catalysis: A Regioselectivity Switch between [2+1] and [2+2] Cycloaddition of Diazocarbonyls with Olefins
作者:Jian Lv、Huixin Qiu、Lirong Wen
DOI:10.1055/a-1786-6496
日期:2022.9
Visible-light-promoted [2+1] and [2+2] cycloadditionreactions of diazocarbonyls with olefins have been developed, affording functionalized cyclopropanes and cyclobutanes, respectively. In visible-light catalysis of Ir(ppy)3, a simple addition of Rh2(OAc)4 switches the regioselectivity from [2+1] to [2+2] cycloaddition with good reactivity and high regioselectivity.
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