Designed Bifunctional Phosphine Ligand-Enabled Gold-Catalyzed Isomerizations of Ynamides and Allenamides: Stereoselective and Regioselective Formation of 1-Amido-1,3-dienes
摘要:
By using designed biphenyl-2-ylphosphines functionalized with a remote basic groups as ligands, N-alkynyl-o-nosylamides are directly converted to (1E,3E)-1-amido-1,3-dienes with excellent diastereoselectivities under gold catalysis. With allenamides as substrates, the gold-catalyzed isomerizations are high yielding and applicable to a broad substrate scope including various nitrogen protecting groups and exhibit unprecedented (3E)-selectivities for the distal C-C double bond and good regioselectivities. Combining this gold catalysis with one-pot Diels-Alder reactions leads to rapid assembly of valuable bicyclic compounds.
Catalytic 1,2-Dicyanation of Alkynes by Palladium(II) under Aerobic Conditions
作者:Shigeru Arai、Takashi Sato、Atsushi Nishida
DOI:10.1002/adsc.200900334
日期:2009.8
various alkynes in the presence of trimethylsilyl cyanide (TMSCN) by palladium(II) catalysis under aerobicconditions is investigated. This reaction includes two cyanation pathways, syn- and anti-cyanopalladation to alkynes that are activated by Pd(II). High syn-selectivity was observed in the reaction using terminal alkynes that have bulky substituents at a propargyl position and aliphatic internal
Gold-Catalyzed Regiodivergent [2 + 2 + 2]-Cycloadditions of Allenes with Triazines
作者:Shiyong Peng、Shengyu Cao、Jiangtao Sun
DOI:10.1021/acs.orglett.6b03691
日期:2017.2.3
Importantly, different types of allenes exhibit distinct selectivity and reactivity for the reactions. Mechanistic investigations reveal that all of the cycloadditions proceed through a stepwise [2 + 2 + 2]-cycloaddition process.
Rhodium/Lewis Acid Catalyzed Regioselective Addition of 1,3-Dicarbonyl Compounds to Internal Alkynes
作者:Wei-Feng Zheng、Qiu-Jing Xu、Qiang Kang
DOI:10.1021/acs.organomet.7b00284
日期:2017.6.26
regioselective addition of 1,3-dicarbonyl compounds to internal alkynescatalyzed by rhodium/Lewisacid catalysts. The corresponding branched/linear allylic alkylation products could be selectively obtained in good yields. Rh–H species were considered to be generated by direct C–H oxidative addition of 1,3-dicarbonyl compounds with rhodium catalyst with the assistance of Lewisacid. Moreover, a retro-allylic