Asymmetric CarbonCarbon Bond‐Forming Reactions

Abstract

The catalytic asymmetric conjugate addition to α , β -unsaturated compounds is one of the most powerful carbon -carbon and carbon -heteroatom bond -forming reactions in organic synthesis. The reaction is enormously useful for the construction of enantioenriched, highly functionalized carbon skeletons for the total syntheses of numerous biologically active compounds. The scope of the reaction is broad, owing to the availability of a large variety of donor and acceptor compounds. The high potential of this synthetic method is evident with the possibility of building multiple stereocenters in a single synthetic operation, and many asymmetric catalytic systems can exhibit high reactivity and stereoselectivity. In this chapter, recent advances in catalytic asymmetric conjugate addition reactions are described according to four categories: (i) conjugate addition of organometallics, (ii) conjugate addition of other carbon -centered nucleophiles, (iii) tandem conjugate addition reactions, and (iv) conjugate addition of heteroatom nucleophiles. 8A.2. CATALYTIC ASYMMETRIC CONJUGATE ADDITION OF ORGANOMETALLICSThe catalytic asymmetric conjugate addition of organometallic reagents to electrophilically activated olefi ns constitutes one of the most powerful methods for carbon -carbon Catalytic Asymmetric Synthesis, Third Edition, Edited by Iwao Ojima

Synthesis of Adjacent Quaternary Stereocenters by Catalytic Asymmetric Allylboration

“…1 Although many excellent, highly stereoselective techniques have been reported, a couple of challenging problems still remained to be solved. Synthesis of quaternary stereocenters, in particular so called "all carbon" stereocenters is still a difficult problem.…”

Stereoretentive Olefin Metathesis: An Avenue to Kinetic Selectivity

“…Olefin metathesis has become an indispensable method for the formation of carbon-carbon double bonds, [1][2][3][4][5] finding use in synthetic organic, [6][7][8] biological, [9][10][11] and materials chemistry. [12][13][14] The ubiquity of olefin metathesis as a synthetic tool has been linked to the evolution of catalysts from ill-defined mixtures to well-characterized molecular species based on molybdenum, ruthenium and tungsten.…”

Synthesis and Evaluation of Sterically Demanding Ruthenium Dithiolate Catalysts for Stereoretentive Olefin Metathesis

“…The employment of olefin metathesis as a method to form carbon–carbon double bonds is pervasive in chemical synthesis. − Development of well-defined transition-metal alkylidenes has provided a scaffold to modify both the steric and electronic properties of the catalysts, delivering access to a wide range of olefin metathesis catalysts. − Recent advancements in catalytic architecture have focused on the construction of stereoselective catalysts. , A longstanding challenge in olefin metathesis was the development of kinetically Z selective olefin metathesis catalysts. Schrock, Hoveyda, and co-workers identified both molybdenum and tungsten systems that performed Z -selective olefin metathesis, − while Grubbs and co-workers developed cyclometalated ruthenium-based catalysts that performed Z -selective olefin metathesis. − Jensen and co-workers reported ruthenium monothiolate catalysts which show kinetic Z selectivity. − All of these catalysts function through the employment of some large ligand which can sterically shield one side of the forming metallacycle, favoring the formation of a syn -ruthenacyclobutane, producing ( Z )-olefins. ,,,− …”