Transition-Metal-Mediated Cascade Reactions: C,C-Dicyclopropylmethylamines by Way of Double C,C-σ-Bond Insertion into Bicyclobutanes
摘要:
The organometallic multicomponent reaction of alkenyl zirconocene, alkynyl imine, and zinc carbenoid in the presence of dimethylzinc leads to novel C,C-dicyclopropylmethylamines. The formation of intermediate bicyclo[1.1.0]butanes represents the first synthetically useful example of a double C,C-sigma-bond insertion, and the increase in structural complexity from starting materials is highlighted by the formation of nine new C,C-bonds in the final product.
Ag-Catalyzed Insertion of Alkynyl Carbenes into C–C Bonds of β-Ketocarbonyls: A Formal C(sp<sup>2</sup>) Insertion
作者:Yongquan Ning、Qingmin Song、Paramasivam Sivaguru、Lizuo Wu、Edward A. Anderson、Xihe Bi
DOI:10.1021/acs.orglett.1c04081
日期:2022.1.21
Here we report a silver-catalyzed alkynyl carbene insertion into β-ketocarbonyls using alkynyl N-nosylhydrazones as alkynyl carbene precursors, which provides access to trisubstituted allenyl ketones. This reaction represents the first example of an alkynyl carbene insertion into a C–C σ bond, affording products homologated with an sp2 carbon center. The products are useful substrates for further transformations
Highly Regio- and Stereoselective Synthesis of <i>Z</i> and <i>E</i> Enol Esters by an Amine-Catalyzed Conjugate Addition–Rearrangement Reaction of Ynals with Carboxylic Acids
作者:He Huang、Xinshuai Zhang、Chenguang Yu、Xiangmin Li、Yueteng Zhang、Wei Wang
DOI:10.1021/acscatal.6b02206
日期:2016.12.2
The broad synthetic utility of labile enolesters demands efficient methods for the stereo- and regioselectivesynthesis of both Z and E isomers. The available synthetic methods dominated by metal catalysis cannot meet the challenge. We wish to report a metal-free organocatalytic divergent approach to both E and Z isomers of enolesters from the same reactant pools with the same catalytic system. A
Gold-catalyzed synthesis of 1,3-disubstituted benzenes through tandem allylation/cyclization reaction of alkynals
作者:Sabyasachi Bhunia、Shariar Md. Abu Sohel、Chao-Chin Yang、Shie-Fu Lush、Fwu-Ming Shen、Rai-Shung Liu
DOI:10.1016/j.jorganchem.2008.10.049
日期:2009.2
Treatment of alkynals with 2-substituted allylsilanes and PPh3AuCl/AgOTf (5/3 mol%) catalyst led to formation of 1,3-disubstituted benzenes efficiently. This reaction sequence comprises an initial allylation of aldehyde, followed by cycloisomerization of enynes; PPh3AuOTf is active in both steps.
Enantioselective Organocatalyzed Oxa-Michael-Aldol Cascade Reactions: Construction of Chiral 4<i>H</i>-Chromenes with a Trifluoromethylated Tetrasubstituted Carbon Stereocenter
作者:Jing Zhang、Manjaly J. Ajitha、Lin He、Kai Liu、Bin Dai、Kuo-Wei Huang
DOI:10.1002/adsc.201400977
日期:2015.3.23
tetrasubstituted carbon center is presented. Chiral secondary amines promote the oxa‐Michael–aldol cascade reactionbetween alkynals and 2‐trifluoroacetylphenols via iminium–allenamine activation to produce pharmaceutically important heterocycles with excellent enantioselectivities. The proposed reaction can be scaled‐up easily with maintenance of the excellent enantioselectivity.