Palladium-Catalyzed Regiodivergent Substitution of Propargylic Carbonates
作者:Theresa M. Locascio、Jon A. Tunge
DOI:10.1002/chem.201603481
日期:2016.12.12
The palladium(0)‐catalyzed, ligand‐controlled, regioselective addition of diaryl acetonitrile pronucleophiles to propargylic carbonates is reported. Selective formation of either terminal 1,3‐dienyl or propargylated products is proposed to arise from a change in reaction mechanism controlled by the denticity of the coordinating ligand.
Highly Enantioselective Cobalt‐Catalyzed (3+2) Cycloadditions of Alkynylidenecyclopropanes
作者:Eduardo Da Concepción、Israel Fernández、José L. Mascareñas、Fernando López
DOI:10.1002/anie.202015202
日期:2021.4.6
Low‐valent cobalt complexes equipped with chiral ligands can efficiently promote highly enantioselective (3+2) cycloadditions of alkyne‐tethered alkylidenecyclopropanes. The annulation allows to assemble bicyclic systems containing five‐membered rings in good yields and with excellent enantiomeric ratios. We also present a mechanistic discussion based on experimental and computational data, which support
配备手性配体的低价钴络合物可以有效地促进炔烃系链的亚烷基环丙烷的高对映选择性(3 + 2)环加成反应。该环状结构可以以高收率和出色的对映体比率组装包含五元环的双环系统。我们还提出了基于实验和计算数据的机制讨论,这些讨论支持Co I / Co III催化循环的参与。
reactions involving nickel‐catalyzed additions of (hetero)arylboronic acids to alkynes, followed by cyclization of the alkenylnickel intermediates onto tethered acyclic ketones to give chiral tertiary‐alcohol‐containing products in high enantioselectivities, are described. The reversible E/Z isomerization of the alkenylnickel intermediates enables overall anti‐arylmetallative cyclization to occur. The ring
Stereoselective Synthesis of Pyrans from Epoxyalkenes: Dual Catalysis with Palladium and Brønsted Acid
作者:Noah A. Setterholm、Frank E. McDonald
DOI:10.1021/acs.joc.8b00026
日期:2018.6.15
We describe regio- and stereoselective cycloisomerizations of alcohols tethered to epoxyalkenes, to construct alkene-substituted pyrans. These transformations are best catalyzed by Pd(PPh3)4 in the presence of phosphite ligands, and with diphenylphosphinic acid as an essential Brønsted acid cocatalyst for activation of the epoxyalkene.
Selective Indium-Mediated 1,2,4-Pentatrien-3-ylation of Carbonyl Compounds for the Efficient Synthesis of Vinyl Allenols
作者:Jisu Park、Sung Hong Kim、Phil Ho Lee
DOI:10.1021/ol802073q
日期:2008.11.6
highly selective synthetic method of functionalized vinyl allenols was developed from the reactions of various carbonylcompounds with organoindium reagent in situ generated from indium and 1-bromopent-4-en-2-yne derivatives. Treatment of vinyl allenols with gold catalyst, dienophile, or indium trihalide produced the functionalized dihydrofuran, cyclohexene, or 2-halo-1,3-diene derivatives in good to