ChemInform Abstract: Ligand Effects on the Chemoselectivity of Transition Metal Catalyzed Reactions of α-Diazo Carbonyl Compounds

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.

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Chemistry of Unsymmetrical C1-Substituted Oxabenzonorbornadienes

Current Organic Synthesis ◽

10.2174/1570179417666210105121115 ◽

2021 ◽

Vol 17 ◽

Author(s):

Austin Pounder ◽

Angel Ho ◽

Matthew Macleod ◽

William Tam

Keyword(s):

Transition Metal ◽

Metal Complexes ◽

Transition Metal Complexes ◽

Substituent Effects ◽

Face Selectivity ◽

Transition Metal Catalyzed ◽

Catalyzed Reactions ◽

Metal Catalyzed ◽

Synthetic Intermediate

: Oxabenzonorbornadiene (OBD) is a useful synthetic intermediate which can be readily activated by transition metal complexes with great face selectivity due to its dual-faced nature and intrinsic angle strain on the alkene. To date, the understanding of transition-metal catalyzed reactions of OBD itself has burgeoned; however, this has not been the case for unsymmetrical OBDs. Throughout the development of these reactions, the nature of C1-substituent has proven to have a profound effect on both the reactivity and selectivity of the outcome of the reaction. Upon substitution, different modes of reactivity arise, contributing to the possibility of multiple stereo-, regio-, and in extreme cases, constitutional isomers which can provide unique means of constructing a variety of synthetically useful cyclic frameworks. To maximize selectivity, an understanding of bridgehead substituent effects is crucial. To that end, this review outlines hitherto reported examples of bridgehead substituent effects on the chemistry of unsymmetrical C1-substituted OBDs.

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Transition metal-catalyzed reactions of N-sulfinyl imines

Tetrahedron Letters ◽

10.1016/j.tetlet.2021.153104 ◽

2021 ◽

pp. 153104

Author(s):

Francisco Foubelo ◽

Carmen Nájera ◽

José M. Sansano ◽

Miguel Yus

Keyword(s):

Transition Metal ◽

Transition Metal Catalyzed ◽

Catalyzed Reactions ◽

Metal Catalyzed

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Transition Metal-Catalyzed α-Position Carbon–Carbon Bond Formations of Carbonyl Derivatives

Catalysts ◽

10.3390/catal10080861 ◽

2020 ◽

Vol 10 (8) ◽

pp. 861 ◽

Cited By ~ 1

Author(s):

Ha-Eun Lee ◽

Dopil Kim ◽

Ahrom You ◽

Myung Hwan Park ◽

Min Kim ◽

...

Keyword(s):

Transition Metal ◽

Carbonyl Compounds ◽

Bond Formation ◽

Chiral Ligand ◽

Catalytic Systems ◽

Carbon Bond ◽

Carbonyl Derivatives ◽

Carbon Carbon Bond ◽

Transition Metal Catalyzed ◽

Metal Catalyzed

α-Functionalization of carbonyl compounds in organic synthesis has traditionally been accomplished via classical enolate chemistry. As α-functionalized carbonyl moieties are ubiquitous in biologically and pharmaceutically valuable molecules, catalytic α-alkylations have been extensively studied, yielding a plethora of practical and efficient methodologies. Moreover, stereoselective carbon–carbon bond formation at the α-position of achiral carbonyl compounds has been achieved by using various transition metal–chiral ligand complexes. This review describes recent advances—in the last 20 years and especially focusing on the last 10 years—in transition metal-catalyzed α-alkylations of carbonyl compounds, such as aldehydes, ketones, imines, esters, and amides and in efficient carbon–carbon bond formations. Active catalytic species and ligand design are discussed, and mechanistic insights are presented. In addition, recently developed photo-redox catalytic systems for α-alkylations are described as a versatile synthetic tool for the synthesis of chiral carbonyl-bearing molecules.

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