5.34 Early Transition Metal Mediated Reductive Coupling Reactions

Micalizio, Glenn C.

doi:10.1016/b978-0-08-097742-3.00535-8

Cited by 10 publications

(11 citation statements)

References 149 publications

(186 reference statements)

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“…These species can be considered as 1,2-dianion equivalents and can be intercepted sequentially by two different electrophiles. Often, the resulting metallacycles can be further functionalized, forming the basis for a diverse set of coupling reactions, such as the Negishi 21,22,45 , Fagan-Nugent 19,83–85 , Kulinkovich 43,86–88 , Pauson-Khand 89–94 and several other stoichiometric coupling reactions of alkynes, alkenes, alkyl halides and carbonyl compounds 18,20 . Although most d 2 early metals exhibit this type of reactivity, low-valent Ti and Zr complexes — in particular, Cp 2 M n (M = Ti, Zr) and (O’’Pr) 2 T II fragments — have seen the most development in this field, and as such the use of such reagents in the total synthesis of natural products has flourished 23,95–97 .…”

Section: Reductive Coupling Reactionsmentioning

confidence: 99%

Modern applications of low-valent early transition metals in synthesis and catalysis

et al. 2018

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Low-valent early transition metals are often intrinsically highly reactive as a result of their strong propensity toward oxidation to more stable high-valent states. Harnessing these highly reducing complexes for productive reactivity is potentially powerful for C-C bond construction, organic reductions, small-molecule activation and many other reactions that offer orthogonal chemoselectivity and/or regioselectivity patterns to processes promoted by late transition metals. Recent years have seen many exciting new applications of low-valent metals through building new catalytic and/or multicomponent reaction manifolds out of classical reactivity patterns. In this Review, we survey new methods that employ early transition metals and invoke low-valent precursors or intermediates in order to identify common themes and strategies in synthesis and catalysis.

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Section: Reductive Coupling Reactionsmentioning

confidence: 99%

Modern applications of low-valent early transition metals in synthesis and catalysis

et al. 2018

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“…The challenge of accomplishing alkene–alkyne cross-coupling (intermolecular) is related to the low reactivity of substituted alkenes in the intermolecular carbometalation step and the established instability of the metallacyclopentene intermediates that result from cross-coupling. 34, 35 As illustrated in Figure 9B, a central feature of Negishi’s alkyne–alkyne coupling process took advantage of this instability. Treatment of an alkyne with the organometallic species generated from addition of 2 equiv.…”

Section: Introductionmentioning

confidence: 99%

Metallacycle-mediated cross-coupling in natural product synthesis

2016

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“…Here, metal-centered [2+2+1] chemistry first delivers an unsaturated metallacyclopentane that can participate in subsequent ring-forming processes. [3] Examples of such include the Reppe reaction, [4] where alkyne trimerization results in the formation of benzenes, and the Pauson–Khand reaction, [5] where cyclopentenones are generated from the union of an alkyne with an alkene and CO (Figure 1B). Despite the now commonly accepted power of these metallacycle-mediated annulative coupling reactions in organic synthesis, they both remain quite limited in scope.…”

Section: Introductionmentioning

confidence: 99%

The Development of Alkoxide‐Directed Metallacycle‐Mediated Annulative Cross‐Coupling Chemistry

Micalizio

Mizoguchi

2016

Israel Journal of Chemistry

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Alkoxide-directed metallacycle-mediated cross-coupling is a rapidly growing area of reaction methodology in organic chemistry. Over the last decade, developments have resulted in > thirty new and highly selective intermolecular (or “convergent”) C–C bond-forming reactions that have established powerful retrosynthetic relationships in stereoselective synthesis. While early studies were focused on developing transformations that forge a single C–C bond by way of a functionalized and unsaturated metallacyclopentane intermediate, recent advances mark the ability to employ this organometallic intermediate in additional stereoselective transformations. Among these more advanced coupling processes, those that embrace the metallacycle in subsequent [4+2] chemistry have resulted in the realization of a number of highly selective annulative cross-coupling reactions that deliver densely functionalized and angularly substituted carbocycles. This review discusses the early development of this chemistry, recent advances in reaction methodology, and shares a glimpse of the power of these processes in natural product synthesis.

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5.34 Early Transition Metal Mediated Reductive Coupling Reactions

Cited by 10 publications

References 149 publications

Modern applications of low-valent early transition metals in synthesis and catalysis

Modern applications of low-valent early transition metals in synthesis and catalysis

Metallacycle-mediated cross-coupling in natural product synthesis

The Development of Alkoxide‐Directed Metallacycle‐Mediated Annulative Cross‐Coupling Chemistry

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