Vicinal Diboronates in High Enantiomeric Purity through Tandem Site-Selective NHC−Cu-Catalyzed Boron−Copper Additions to Terminal Alkynes

Lee, Yun-Mi; Jang, Hwanjong; Hoveyda, Amir H.

doi:10.1021/ja9089928

Cited by 238 publications

(79 citation statements)

References 21 publications

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“…11a Asymmetric catalytic approaches to dimetalation have relied primarily on noble metal (Pt, Rh, and Pd) catalysis 11. Very recently, Hoveyda and co‐workers disclosed a copper‐catalyzed double borylcupration to alkynes that afforded 1,2‐diboronated alkanes in high enantioselectivities 12. Borylcupration has also been widely employed as an elegant strategy for enantioselective hydro/difunctionalization of alkenes,13 including hydroboration (Hoveyda),14 aminoboration (Miura),15 and borylcarbonation (Lin) 16.…”

Section: Methodsmentioning

confidence: 99%

Copper‐Catalyzed Asymmetric Three‐Component Borylstannation: Enantioselective Formation of CSn Bond

Jia

Cao

Wang

et al. 2015

Chemistry A European J

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In summary, a first copper-catalyzed synthesis of a-aryl-b-borylstannane compounds was accomplished through three-component borylstannation of aryl-substituted alkenes. In the exploration of an asymmetric variant, chiral sulfinylphosphine ligands proved advantageous in controlling stereochemistry of BÀCu addition and in promoting transmetalation of enantioenriched alkylÀCu species. The stereochemical outcome supported a sequential syn-borylcupration and configuration-retentive transmetalation mechanism. Moreover, a-chiral b-borylstannanes were easily transformed into a diverse array of secondary alkylstannanes and triarylethane with high enantiomeric purity. The applications of chiral sulfinylphosphine ligands to other tandem CuÀB addition reactions are currently under investigation in our group.Configurationally stable nonracemic organometallic compounds (organoboron, organosilane, and organotin) [1] are emerging as a class of important chiral reagents. Their carbonmetal bonds can be readily transformed to stereogenic carbon-carbon [2] and carbon-heteroatom bonds, [3] providing novel and concise routes to syntheses of natural products and chiral drugs. Among these organometallic compounds, secondary alkylstannanes are configurationally robust and easily stored, and have been utilized in many asymmetric transformations, such as Stille-type cross-coupling reactions, [4] allylstannations, [5] and transmetalations to other organometallic species.[6]Conventional methods to reach optically active organostannanes include chiral resolution, [4f] substrate control, [4c, 7] and reagent induction, [8] whereas asymmetric catalysis has been rather less thoroughly investigated. To date, only two cases relating to chiral secondary cyclic alkylstannane synthesis have been reported. In 2004, Gevorgyan and co-workers developed a Rh I -catalyzed enantioselective hydrostannation of cyclopropene to generate cyclopropylstannanes.[9a] More recently, Studer and co-workers [9b] reported a Cu I -catalyzed asymmetric annulation of 2-nitrosopyridine and allylstannane to furnish tin-substituted isoxazolidines (Scheme 1 a,b). However, to our knowledge, a general and versatile catalytic asymmetric method for the construction of acyclic alkylstannanes remains unreported.[10] Herein we present a new Cu-catalyzed asymmetric dimetalation (three-component reaction) strategy to access to enantiomerically enriched organostannanes (Scheme 1 c).Bis-metalated alkene moieties are of increasing importance in the preparation of medical reagents and complex molecules through cascade transformations. [2g, 11a] Asymmetric catalytic approaches to dimetalation have relied primarily on noble metal (Pt, Rh, and Pd) catalysis.[11] Very recently, Hoveyda and co-workers disclosed a copper-catalyzed double borylcupration to alkynes that afforded 1,2-diboronated alkanes in high enantioselectivities.[12] Borylcupration has also been widely employed as an elegant strategy for enantioselective hydro/difunctionalization of alkenes, [13] including hydro...

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Section: Methodsmentioning

confidence: 99%

Copper‐Catalyzed Asymmetric Three‐Component Borylstannation: Enantioselective Formation of CSn Bond

Jia

Cao

Wang

et al. 2015

Chemistry A European J

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“…As previously described, hydroboration of multiple carbon-carbon bond is a straightforward process to access organoboranes [66]. These potent reagents find many applications, such as in the Suzuki-Miyaura cross-coupling reaction.…”

Section: Boration Of Alkynesmentioning

confidence: 99%

Copper–NHC complexes in catalysis

Lazreg

Nahra

Cazin

2015

Coordination Chemistry Reviews

238

110

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“…2); the desired product cannot be accessed through catalytic hydrogenation of the corresponding alkyne (see also 10c ). Cu-catalyzed site- and enantioselective dihydroboration xviii furnishes 16 [98:2 enantiomeric ratio (e.r. )], which has been previously converted to C18 (plasm)-16:0 (PC) in four steps and 86% overall yieldxix.…”

Section: Synthesis Of Natural Product C18 (Plasm)-16:0 (Pc)mentioning

confidence: 99%

Catalytic Z-selective olefin cross-metathesis for natural product synthesis

Meek

O’Brien

Llaveria

et al. 2011

Nature

Self Cite

376

218

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Alkenes are found in a great number of biologically active molecules and are employed in numerous transformations in organic chemistry. Many olefins exist as E or higher energy Z isomers. Catalytic procedures for stereoselective formation of alkenes are therefore valuable; nonetheless, methods for synthesis of 1,2-disubstituted Z olefins are scarce. Here we report catalytic Z-selective cross-metathesis reactions of terminal enol ethers, which have not been reported previously, and allylic amides, employed thus far only in E-selective processes; the corresponding disubstituted alkenes are formed in up to >98% Z selectivity and 97% yield. Transformations, promoted by catalysts that contain the highly abundant and inexpensive molybdenum, are amenable to gram scale operations. Use of reduced pressure is introduced as a simple and effective strategy for achieving high stereoselectivity. Utility is demonstrated by syntheses of anti-oxidant C18 (plasm)-16:0 (PC), found in electrically active tissues and implicated in Alzheimer’s disease, and the potent immunostimulant KRN7000.

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Vicinal Diboronates in High Enantiomeric Purity through Tandem Site-Selective NHC−Cu-Catalyzed Boron−Copper Additions to Terminal Alkynes

Cited by 238 publications

References 21 publications

Copper‐Catalyzed Asymmetric Three‐Component Borylstannation: Enantioselective Formation of CSn Bond

Copper‐Catalyzed Asymmetric Three‐Component Borylstannation: Enantioselective Formation of CSn Bond

Copper–NHC complexes in catalysis

Catalytic Z-selective olefin cross-metathesis for natural product synthesis

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