Structural factors affecting the selectivities in the palladium (II) catalyzed cyclization of N-alkenyl-2-alkynamides
作者:Huanfeng Jiang、Shengming Ma、Guoxin Zhu、Xiyan Lu
DOI:10.1016/0040-4020(96)00648-5
日期:1996.8
Palladiumcatalyzedcyclization of N-alkenyl 2-alkynamides occurred smoothly in the presence of CuCl2 and LiCl affording α-chloroalkylidene-γ-butyrolactams and α-chloroalkylidene-δ-valerolactams valerolactams stereoselectively. The regioselectivity of the intramolecular C-C double bond insertion was influenced by the substituent group on the substrate. When an alkyl group was introduced into the 1'-position
Efficient Construction of Five-Membered Aromatic and Nonaromatic Heterocycles from 1,6-Enynes by a Palladium-Catalyzed Domino Coupling/Cycloisomerization Process
作者:Tuan-jie Meng、Yimin Hu、Shaowu Wang
DOI:10.1021/jo9020776
日期:2010.2.5
General and efficient methods for the construction of five-membered aromatic and nonaromatic heterocycles by palladium-catalyzed coupling/cycloisomerization of 1,6-enynes and aryl halides have been developed. Results indicate that substituents at the terminus of the alkynes have a significant effect on the selective formation of the products.
Enantioselective Reductive Cyclization of 1,6-Enynes via Rhodium-Catalyzed Asymmetric Hydrogenation: C−C Bond Formation Precedes Hydrogen Activation
作者:Hye-Young Jang、Freddie W. Hughes、Hegui Gong、Junmei Zhang、Jennifer S. Brodbelt、Michael J. Krische
DOI:10.1021/ja042645v
日期:2005.5.1
Asymmetric hydrogenation of 1,6-enynes using chirally modified cationic rhodium precatalysts enables enantioselective reductive cyclization to afford alkylidene-substituted carbocycles and heterocycles in a completely atom economical fashion. Good to excellent yields and exceptional levels of asymmetric induction are observed across a structurally diverse set of substrates. Mechanistic studies involving
Rhodium-catalyzed cycloaddition of 1,6-enynes with 2-bromophenylboronic acids: synthesis of a multi-substituted dihydronaphthalene scaffold
作者:Xianjie Fang、Chaolong Li、Xiaofeng Tong
DOI:10.1039/b910532h
日期:——
A formal [2 + 2 + 2] cycloaddition of a 1,6-enyne with 2-bromophenylboronic acid has been realized to construct a multi-substituted dihydronaphthalene scaffold, in which the direct reductive elimination mechanism of aryl-Rh(III)-Csp3 species has been established to form an aryl-Csp3 bond.
The Pd-catalyzed cyclizations of 1,6-enynes are efficient reactions for the synthesis of alpha-methylene-gamma-butyrolactones and lactams. The effects of solvent, proton source, chloride concentration, and temperature on the protonolysis of the carbon-Pd bond were investigated and the optimal reaction conditions were identified. We showed that imidazolium-type ionic liquids played an important role in the reaction both as a ligand for the palladium catalyst and as a solvent. The crystal structure of the Pd complex was obtained and the reaction mechanisms were discussed. (C) 2008 Elsevier Ltd. All rights reserved.