Transition-metal-catalyzed cleavage of carbon–selenium bond and addition to alkynes and allenes

2010 ◽  
Vol 82 (3) ◽  
pp. 565-575 ◽  
Author(s):  
Shin-ichi Fujiwara ◽  
Masashi Toyofuku ◽  
Hitoshi Kuniyasu ◽  
Nobuaki Kambe
Keyword(s):  
Transition Metal ◽  
Membered Ring ◽  
Ring Formation ◽  
Reaction Pathways ◽  
Unsaturated Hydrocarbons ◽  
Transition Metal Catalyzed ◽  
Metal Catalyzed ◽  
High Stereoselectivity

This account summarizes our recent results on transition-metal-catalyzed cleavage of C–Se bond and addition to unsaturated hydrocarbons such as alkynes and allenes. Pd(0)-catalyzed intramolecular carbamoselenation of alkynes forms four- to eight-membered α-alkylidenelactams. Interestingly, four-membered ring formation is faster than five- and six-membered ring formation. Intramolecular vinylselenation of suitably structured alkynes offers pathways to conjugated δ-lactam frameworks. Electron-withdrawing groups on the vinyl moiety are essential to promote this reaction. Intermolecular 1,2-addition of selenol esters onto allenes proceeds with excellent regioselectivity and high stereoselectivity in the presence of a Pd(0) catalyst, producing functionalized allyl selenides. In addition, Pd(0)-catalyzed intramolecular selenocarbamoylation of allenes gives α,β-unsaturated γ- and δ-lactams with perfect regioselectivity. The scope and limitations, as well as reaction pathways, are discussed.

Transition-Metal-Catalyzed Asymmetric Allylation of Carbonyl Compounds with Unsaturated Hydrocarbons

Synthesis ◽  
2017 ◽  
Vol 50 (05) ◽  
pp. 956-967 ◽  
Author(s):  
Liu-Zhu Gong ◽  
Pu-Sheng Wang ◽  
Meng-Lan Shen
Keyword(s):  
Transition Metal ◽  
Carbonyl Compounds ◽  
Building Blocks ◽  
Asymmetric Allylation ◽  
Unsaturated Hydrocarbons ◽  
Homoallylic Alcohols ◽  
Carbon Carbon Bonds ◽  
Transition Metal Catalyzed ◽  
Metal Catalyzed ◽  
Direct Use

The asymmetric allylation of carbonyl compounds is an important process for the formation of carbon–carbon bonds, generating optically active homoallylic alcohols that are versatile building blocks with widespread applications in organic synthesis. The use of readily available unsaturated hydrocarbons as allylating reagents in the transition-metal-catalyzed asymmetric allylation has received increasing interest as either a step- or an atom-economy alternative. This review summarizes transition-metal-catalyzed enantioselective allylations on the basis of the ‘indirect’ and ‘direct’ use of simple unsaturated hydrocarbons (include dienes, allenes, alkynes, and alkenes) as allylating reagents, with emphasis on highlighting conceptually novel reactions.1 Introduction2 ‘Indirect’ Use of Unsaturated Hydrocarbons in Asymmetric Allylation of Carbonyl Compounds2.1 Enantioselective Allylation with 1,3-Dienes2.2 Enantioselective Allylation with Allenes2.3 Enantioselective Allylation with Alkenes3 ‘Direct’ Use of Unsaturated Hydrocarbons in Asymmetric Allylation of Carbonyl Compounds3.1 Enantioselective Allylation with 1,3-Dienes3.2 Enantioselective Allylation with Allenes3.3 Enantioselective Allylation with Alkynes3.4 Enantioselective Allylation with Alkenes4 Conclusions

scholarly journals Construction 7-Membered Ring via Ni-Al Bimetal-Enabled C-H Cyclization for Synthesis of Tricyclic Imidazoles

2021 ◽  
Author(s):  
Mengchun Ye ◽  
Jiang-Fei Li ◽  
Wei-Wei Xu ◽  
Rong-Hua Wang ◽  
Yue Li ◽  
...  
Keyword(s):  
Transition Metal ◽  
Membered Ring ◽  
Bioactive Molecules ◽  
Direct Construction ◽  
Transition Metal Catalyzed ◽  
Metal Catalyzed ◽  
Medium Ring ◽  
Ring Synthesis

Abstract The construction of 7-membered ring via direct C7−H cyclization of benzoimidazoles with alkenes would provide a more atom- and step economical route to tricyclic imidazoles and derivatives that widely exist in a broad range of bioactive molecules. However, transition metal-catalyzed C−H cyclization for medium-ring synthesis has been limited to reactive C−H bonds, instead, the activation of unreactive C−H bonds towards medium synthesis still remains an elusive challenge. Herein, we report a direct construction of 7-membered rings via Ni−Al co-catalyzed unreactive C7−H cyclization of benzoimidazoles with alkenes, providing a series of tricyclic imidazoles in 40−98% yield and with up to 95:5 er.

scholarly journals Construction 7-membered ring via Ni–Al bimetal-enabled C–H cyclization for synthesis of tricyclic imidazoles

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Jiang-Fei Li ◽  
Wei-Wei Xu ◽  
Rong-Hua Wang ◽  
Yue Li ◽  
Ge Yin ◽  
...  
Keyword(s):  
Transition Metal ◽  
Membered Ring ◽  
Bioactive Molecules ◽  
Direct Construction ◽  
Transition Metal Catalyzed ◽  
Metal Catalyzed ◽  
Medium Ring ◽  
Ring Synthesis

AbstractThe construction of 7-membered ring via direct C7–H cyclization of benzoimidazoles with alkenes would provide a more atom- and step-economical route to tricyclic imidazoles and derivatives that widely exist in a broad range of bioactive molecules. However, transition metal-catalyzed C–H cyclization for medium-ring synthesis has been limited to reactive C–H bonds, instead, the activation of unreactive C–H bonds towards medium synthesis still remains an elusive challenge. Herein, we report a direct construction of 7-membered rings via Ni–Al co-catalyzed unreactive C7–H cyclization of benzoimidazoles with alkenes, providing a series of tricyclic imidazoles in 40–98% yield and with up to 95:5 er.

Chelation-assisted transition metal-catalysed C–H chalcogenylations

2020 ◽  
Vol 7 (8) ◽  
pp. 1022-1060 ◽  
Author(s):  
Wenbo Ma ◽  
Nikolaos Kaplaneris ◽  
Xinyue Fang ◽  
Linghui Gu ◽  
Ruhuai Mei ◽  
...  
Keyword(s):  
Transition Metal ◽  
Recent Advances ◽  
Site Selectivity ◽  
Transition Metal Catalyzed ◽  
Metal Catalyzed

This review summarizes recent advances in C–S and C–Se formations via transition metal-catalyzed C–H functionalization utilizing directing groups to control the site-selectivity.

Monodentate Trialkylphosphines: Privileged Ligands in Metal-catalyzed Crosscoupling Reactions

2020 ◽  
Vol 24 (3) ◽  
pp. 231-264 ◽  
Author(s):  
Kevin H. Shaughnessy
Keyword(s):  
Transition Metal ◽  
Cross Coupling ◽  
Coupling Reactions ◽  
Cross Coupling Reactions ◽  
Aryl Bromides ◽  
Wide Range ◽  
Sterically Demanding ◽  
Transition Metal Catalyzed ◽  
Catalyzed Reactions ◽  
Metal Catalyzed

Phosphines are widely used ligands in transition metal-catalyzed reactions. Arylphosphines, such as triphenylphosphine, were among the first phosphines to show broad utility in catalysis. Beginning in the late 1990s, sterically demanding and electronrich trialkylphosphines began to receive attention as supporting ligands. These ligands were found to be particularly effective at promoting oxidative addition in cross-coupling of aryl halides. With electron-rich, sterically demanding ligands, such as tri-tertbutylphosphine, coupling of aryl bromides could be achieved at room temperature. More importantly, the less reactive, but more broadly available, aryl chlorides became accessible substrates. Tri-tert-butylphosphine has become a privileged ligand that has found application in a wide range of late transition-metal catalyzed coupling reactions. This success has led to the use of numerous monodentate trialkylphosphines in cross-coupling reactions. This review will discuss the general properties and features of monodentate trialkylphosphines and their application in cross-coupling reactions of C–X and C–H bonds.

Transition-Metal-Catalyzed Oxidative and Decarboxylative Acylations through sp2 C-H Bond Activation

2015 ◽  
Vol 20 (5) ◽  
pp. 471-511 ◽  
Author(s):  
Satyasheel Sharma ◽  
Neeraj Kumar Mishra ◽  
Youngmi Shin ◽  
In Su Kim
Keyword(s):  
Transition Metal ◽  
Bond Activation ◽  
Transition Metal Catalyzed ◽  
Metal Catalyzed
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