Stereoselective Pinacol Coupling of (Propargyl aldehyde)Co<sub>2</sub>(CO)<sub>6</sub> Complexes

Lake, Katherine E.; Dorrell, M.; Blackman, NA; Khan, Masood A.; Nicholas, Kenneth M.

doi:10.1021/om030392t

Cited by 14 publications

(8 citation statements)

References 22 publications

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“…High syn diastereoselectivity has also been observed in the SmI 2 -promoted dimerizations of other similar organometallic aldehydes, such as ferrocenecarboxaldehyde, 25,26 (benzaldehyde)Cr(CO) 3 , 25 (di- enal)Fe(CO) 3 complexes, 25 and (propargyl aldehyde)Co(CO) 6 complexes. 27 Stereoselectivity in SmI 2 -promoted pinacolization has been described as arising from binding of the Sm III ketyl to the unreduced second aldehyde prior to C-C bond formation and the subsequent second reduction. 25 Aldehyde 10 could be converted to its benzyl imine (13), which underwent reductive dimerization with SmI 2 to form diamine 14 (Scheme 4), albeit in diminished yield (44%) and with poor (1.1:1) diastereoselectivity, again, as expected from the literature.…”

Section: Resultsmentioning

confidence: 99%

Generation and Trapping of Radicals Derived from Cyclobutadieneiron Tricarbonyl

Byers¹,

Sontum²,

Dimitrova³

et al. 2006

Organometallics

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Section: Resultsmentioning

confidence: 99%

Generation and Trapping of Radicals Derived from Cyclobutadieneiron Tricarbonyl

Byers¹,

Sontum²,

Dimitrova³

et al. 2006

Organometallics

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“…While transition metal complexes based on palladium (0) [23] nickel(0), [24] and ruthenium(II) [25] are known to facilitate the ATC reaction of alkyl halides, catalytic developments for a prop- argylic variation have been scarce. The sole literature example using a transition metal catalyst is a recent study that employed Fe(II), specifically dppf (1,1'-bis(diphenylphosphino)ferrocene), as a catalyst for the cyclization of allyl and propargyl chlorides (44) in trifluorotoluene at 120°C, the propargyl chlorides giving exocyclic allene-bearing pyrrolidines (45) in moderate yields (Scheme 11). [26] The iron sandwich compound was selected in order to discourage oxidative addition and subsequent formation of an allyl-metal species.…”

Section: Atom Transfer Cyclization and Addition Reactionsmentioning

confidence: 99%

“…[43] Nicholas et al have developed a stereoselective pinacol coupling using propargyl aldehyde-cobalt complexes. [44] The aldehyde cobalt complexes undergo pinacol coupling with various reductants giving syn (dl)-acetylenic diol-cobalt complexes which on treatment with (NH 4 ) 2 Ce(NO 3 ) 6 decomplexes the cobalt to furnish diols (Table 5). A single pinacol diaster-eomer (syn) was isolated in all instances, and the yields of 92 are moderate and are independent of the substrate complex or the reductant used.…”

Section: Pinacol and Mcmurry Coupling Reactionsmentioning

confidence: 99%

Propargyl Radicals in Organic Synthesis

et al. 2021

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The appearance of propargyl radicals as synthetic intermediates has increased in recent years from a structural curiosity to a frequent occurrence. This minireview covers the synthetically relevant organic chemistry involving the intermediacy of propargyl radicals. The review is organized by the process employed in radical generation, including H-atom abstraction, propargyl-X homolyses, radical addition to enynes, reduction of polar C=X bonds, reductions of stable carbocations, and metalmediated coupling reactions. The relevant mechanisms of generation and reaction are discussed, as are applications in syntheses of target molecules of interest.

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“…Hence, by protecting the reactive triple bond of the acetylene compounds with the octacarbonyldicobalt, many kinds of reactions such as reductions, 122 -124 Friedel-Crafts reactions, 122,125 rearrangements, 126 fluorinations, 127 1,3dipolar cycloaddition reactions, 128 Grignard reactions, 129 hydrolyses, 130 oxidations, 131 amidations, 131 pinacol coupling reactions, 132 carbonylative cyclizations, 133 metathesis 134 and radical reactions, 135 have been reported. These many reactions with ocatacarbonyldicobalt for protection of the reactive acetylene triple bond have been applied in organic syntheses.…”

Section: Omaementioning

confidence: 99%

Three characteristic reactions of organocobalt compounds in organic synthesis

Omae

2007

Applied Organom Chemis

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Organocobalt compounds in organic synthesis have three characteristic reactions. The first occurs because cobalt has a high affinity to carbon-carbon π -bonds or carbon-nitrogen π -bonds. The second occurs because cobalt has a high affinity to carbonyl groups. The third is due to cobalt easily tending to form square-planar bipyramidal six-coordination structures with four nitrogen atoms or two nitrogen atoms and two oxygen atoms at the square-planar position, and to bond with one or two carbon atoms at the axial position. The first characteristic reactions are the representative reactions of organocobalt compounds with a mutually bridged bond between the two π -bonds of acetylene and the cobalt-cobalt bond of hexacarbonyldicobalt. These are reactions with a Co 2 (CO) 6 INTRODUCTIONOrganometallic intramolecular coordination compounds, especially five-membered ring compounds of organotin compounds, have been studied since 1965, and many reviews 1 -13 and some books 14 -16 have published on the subject. These compounds are mainly synthesized by cyclometalation reactions with transition metal compounds. The first publication on this subject is generally considered to be the reaction of diazobenzene with nick elocene by Kleiman and Dubeck 17 in 1963 as shown in equation (1).*Correspondence to: Iwao Omae, Nihon Pharmaceutical University, 10281, Komuro, Ina-cho, Saitama, An earlier article on the direct synthesis of 2-phenyl-3-indazolinone by carbonylation of azobenzene with a cobalt Materials, Nanoscience and CatalysisThree characteristic reactions of organocobalt compounds 319 carbonyl catalyst, as shown in equation (2), was published in 1956. 18 It was also synthesized in 1967 through a twostep reaction, that is, (i) cyclopalladation of azobenzene via the five-membered ring product, and (ii) carbonylation, as shown in equation (3). 19From these two reactions, the former reaction [equation (2)] is presumed also to proceed via cyclometallation, that is, cyclocobaltation with the cobalt carbonyl catalyst, as shown in equation (4). Actually, many cyclomatalations with cobalt compounds have been reported. 20 -35 For example, a similar cyclometalated organocobalt compound was prepared by the reaction of azobenzene with methyltetra(trimethylphosphine)cobalt, as shown in equation (5). 20 Further, one year previously, in 1955, the same type of heterocyclic compound was prepared by the same type of carbonylation reaction with an organocobalt compound, as shown in equation (6). 36 This publication by Murahashi 36 may be considered to be the first reaction relating cyclometalation reactions.In the chemical industry, organocobalt is an essential constituent in many important catalysts. Specifically, they are key components in the multimillion-pound technology of hydroformylation; that is, the catalytic transformation of olefins into aldehydes using homogeneous catalysts. This article reports on three characteristic reactions of the organocobalt compounds in organic syntheses on the basis of their structures and reactivities...

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Stereoselective Pinacol Coupling of (Propargyl aldehyde)Co₂(CO)₆ Complexes

Cited by 14 publications

References 22 publications

Generation and Trapping of Radicals Derived from Cyclobutadieneiron Tricarbonyl

Generation and Trapping of Radicals Derived from Cyclobutadieneiron Tricarbonyl

Propargyl Radicals in Organic Synthesis

Three characteristic reactions of organocobalt compounds in organic synthesis

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Stereoselective Pinacol Coupling of (Propargyl aldehyde)Co2(CO)6 Complexes

Cited by 14 publications

References 22 publications

Generation and Trapping of Radicals Derived from Cyclobutadieneiron Tricarbonyl

Generation and Trapping of Radicals Derived from Cyclobutadieneiron Tricarbonyl

Propargyl Radicals in Organic Synthesis

Three characteristic reactions of organocobalt compounds in organic synthesis

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Product

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Stereoselective Pinacol Coupling of (Propargyl aldehyde)Co₂(CO)₆ Complexes