Stereospecific Pd-Catalyzed Cross-Coupling Reactions of Secondary Alkylboron Nucleophiles and Aryl Chlorides

Li, Ling; Zhao, Shibin; Joshi‐Pangu, Amruta; Diane, Mohamed; Biscoe, Mark R.

doi:10.1021/ja508815w

Cited by 214 publications

(99 citation statements)

References 50 publications

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“…Alkyltrifluoroborates with different ring sizes and steric demands were efficiently coupled with aryl-and heteroaryl bromides. In contrast to previous results for similar transformations under traditional Pd-catalyzed conditions [13,16], (±)-2-methylcycloalkyltrifluoroborates afforded the desired products without rearrangement, giving only the racemic, trans-diastereomer (Scheme 6). Importantly, 23 39 alkyltrifluoroborates in which the alkyl group possesses greater s-character have unfavorable redox potentials (because radicals generated from these species are less stable than those with less s-character), thus inhibiting radical formation.…”

Section: Cross-coupling With Organotrifluoroboratescontrasting

confidence: 85%

“…Consequently, molecular complexity can be built into various functionalized core reagents, providing more diversity by which targeted molecular platforms can be constructed. Moreover, when compared to other boron species, [14][15][16], and successful protocols still require harsh conditions (excess base, high temperatures) to overcome a slow transmetalation.…”

Section: Cross-coupling With Organotrifluoroboratesmentioning

confidence: 99%

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Photoredox Catalysis in Nickel-Catalyzed Cross-Coupling

Cavalcanti

Molander

2016

Top Curr Chem (Z)

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The traditional transition metal-catalyzed cross-coupling reaction, although well suited for C(sp2)-C(sp2) cross-coupling, has proven less amenable toward coupling of C(sp3)-hybridized centers, particularly using functional group tolerant reagents and reaction conditions. The development of photoredox/Ni dual catalytic methods for cross-coupling has opened new vistas for the construction of carbon-carbon bonds at C(sp3)-hybridized centers. In this chapter, a general outline of the features of such processes is detailed.

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Section: Cross-coupling With Organotrifluoroboratescontrasting

confidence: 85%

Section: Cross-coupling With Organotrifluoroboratesmentioning

confidence: 99%

Photoredox Catalysis in Nickel-Catalyzed Cross-Coupling

Cavalcanti

Molander

2016

Top Curr Chem (Z)

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“…Here, a vast array of natural products, pharmaceutical agents, and druglike compounds were synthesized through cross-coupling procedures strictly limited to sp 2 -and primary sp 3 -hybridized organoborons. Despite the tremendous power shown in this report, this limitation handicaps the potential impact of the technology, because no general protocol exists for the Suzuki cross-coupling of secondary alkylboron compounds (30,31). Thus, although simple hydrocarbon substructures often provide satisfactory yields, organoboron compounds displaying α-branching [e.g., 17b; the methods of Biscoe (31) and Molander (30) for Suzuki cross-coupling of secondary alkylboron reagents generate isomerized side products with branched substrates] and a variety of functional groups and/or heteroatoms (e.g., 17c and 17d) cannot be crosscoupled using conventional technologies.…”

mentioning

confidence: 98%

Protecting group-free, selective cross-coupling of alkyltrifluoroborates with borylated aryl bromides via photoredox/nickel dual catalysis

Yamashita

Tellis

Molander

2015

Proc. Natl. Acad. Sci. U.S.A.

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Orthogonal reactivity modes offer substantial opportunities for rapid construction of complex small molecules. However, most strategies for imparting orthogonality to cross-coupling reactions rely on differential protection of reactive sites, greatly reducing both atom and step economies. Reported here is a strategy for orthogonal cross-coupling wherein a mechanistically distinct activation mode for transmetalation of sp3-hybridized organoboron reagents enables C-C bond formation in the presence of various protected and unprotected sp2-hybridized organoborons. This manifold has the potential for broad application, because orthogonality is inherent to the activation mode itself. The diversification potential of this platform is shown in the rapid elaboration of a trifunctional lynchpin through various transition metal-catalyzed processes without nonproductive deprotection or functional group manipulation steps.

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“…[20,21] We then considered the possibility of exploiting the high level of substrate control to selectively generate the other diastereomeric boronic ester 15 a.W eb elieve that the high diastereoselectivity in the reaction of 9 with 10 arises from akinetically controlled stereoselective boronate complex formation in which (S)-9 reacts at af aster rate than (R)-9 leading to the selective formation of boronate complex (S)-18 (Scheme 3A). Subsequent 1,2-migration then provides benzylic boronic ester 19 b,the neopentyl glycol analogue of 15 b.Inan attempt to reverse this selectivity,w ep roposed to react lithiated chloromethyl benzoate 20 in place of 9 (Scheme 3B).…”

Section: Angewandte Chemiementioning

confidence: 99%

Short Enantioselective Total Synthesis of Tatanan A and 3‐epi‐Tatanan A Using Assembly‐Line Synthesis

2016

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Short and highly stereoselective total syntheses of the sesquilignan natural product tatanan Aa nd its C3 epimer are described. An assembly-line synthesis approach,using iterative lithiation-borylation reactions,w as applied to install the three contiguous stereocenters with high enantio-and diastereoselectivity.One of the stereocenters was installed using aconfigurationally labile lithiated primary benzyl benzoate,r esulting in high levels of substrate-controlled (undesired) diastereoselectivity.However,reversal of selectivity was achieved by using an ovel diastereoselective Matteson homologation. Stereospecific alkynylation of ah indered secondary benzylic boronic ester enabled completion of the synthesis in at otal of eight steps.Iterative strategies are highly attractive for the synthesis of complex molecules, [1] particularly when minimal or no functional-group manipulations between chain-extension steps are required. [2,3] Iterative aldol reactions provide one such strategy, [3] but if the target molecule is devoid of appropriate functional-group handles,a lternative methodologies are required. We recently reported an iterative strategy for the homologation of boronic esters that notably does not require any functional-group manipulations between chain-extension steps. [4,5] Theprocess involves the repeated addition of chiral lithiated carbamates or triisopropylbenzoate (TIB) esters and leads to carbon chains bearing multiple contiguous methylsubstituted stereogenic centers ( Figure 1A). This approach enabled the generation of extended chains of vicinal stereocenters (up to 10) with complete control over the relative and absolute stereochemistry and applications to complex natural products have also been reported. [6] Thepower of iterative homologation of boronic esters lies in its versatility since other alkyl groups can be easily incorporated simply by varying the groups on the lithiated benzoate reagent. In extending the reach of this method, we sought to introduce aryl substituents as this would enable access to an even broader array of targets,f or example tatanan A( 1)a nd iryantherin K( 2)( Figure 1B). [7,8] We targeted the sesquilignan tatanan A( 1)a st his structurally unique molecule had been reported to display potent glucokinase-activating properties,t hereby having implications for the development of antihyperglycemic drugs, although its bioactivity has since been questioned by Zakarian, who also reported its first synthesis. [9] Thes ynthesis of such am olecule would require homologation with am ixture of alkyl-and aryl-substituted lithiated benzoates.W hilst alkyl-substituted lithiated benzoates were known to be effective in assembly-line synthesis,l ittle was known about the aryl-substituted lithiated benzoates. [10,11] Such species present additional challenges in that, unlike the alkylsubstituted lithiated benzoates,t hey are configurationally

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Stereospecific Pd-Catalyzed Cross-Coupling Reactions of Secondary Alkylboron Nucleophiles and Aryl Chlorides

Cited by 214 publications

References 50 publications

Photoredox Catalysis in Nickel-Catalyzed Cross-Coupling

Photoredox Catalysis in Nickel-Catalyzed Cross-Coupling

Protecting group-free, selective cross-coupling of alkyltrifluoroborates with borylated aryl bromides via photoredox/nickel dual catalysis

Short Enantioselective Total Synthesis of Tatanan A and 3‐epi‐Tatanan A Using Assembly‐Line Synthesis

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