A novel regiospecific aryl ketone synthesis by the reaction of arylborate anions with acyl chlorides

Negishi, Ei‐ichi; Abramovitch, Akiva; Merrill, R. E.

doi:10.1039/c39750000138

Cited by 32 publications

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“…The earliest applications of transition-metal-free couplings can be found in pioneering work from the groups of Levy, [67][68][69] Negishi, [70,71] Suzuki, [72][73][74] Ishikura, [75][76][77][78][79][80] and others. [81][82][83] These examples showed that aryl and alkylboranes can undergo arylation processes by treatment with electronrich aryllithiums (e.g., 2-lithiofuran, 2-lithiothiophene) followed by electrophilic trapping (Scheme 21).…”

Section: Pioneering Workmentioning

confidence: 99%

Stereospecific Couplings of Secondary and Tertiary Boronic Esters

2014

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Section: Pioneering Workmentioning

confidence: 99%

Stereospecific Couplings of Secondary and Tertiary Boronic Esters

2014

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“…Carboxylic acids can be converted directly to alkyl ketones by treatment with excess organolithium compounds and Grignard reagents, but such protocols severely limit functional group incorporation in both partners. Greater toleration of sensitive functional groups can derive from reaction of stoichiometric alkylmetallics (e.g., R-[M], M = Cu, Mn, Zn, Zr, B) with activated carboxylic acid derivatives such as acyl halides, anhydrides, thioesters, or amides. Further enhancements can stem from transition metal-catalyzed protocols, which overcome many limitations associated with traditional approaches to aliphatic ketones .…”

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confidence: 99%

Direct Conversion of Carboxylic Acids to Alkyl Ketones

Amani

Molander

2017

Org. Lett.

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An efficient and mild method for acyl–Csp3 bond formation based on the direct conversion of carboxylic acids has been established. This protocol is enabled by the synergistic, Ir-photoredox/nickel catalytic cross-coupling of in situ activated carboxylic acids and alkyltrifluoroborates. This versatile method is amenable to the cross-coupling of structurally diverse carboxylic acids with various potassium alkyltrifluoroborates, affording the corresponding ketones with high yields. In this operationally simple cross-coupling protocol, aliphatic ketones are obtained in one step from bench stable, readily available carboxylic acids.

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“…To trigger a stereospecific 1,2-metallate rearrangement, a positive charge needs to be generated at the aromatic B-bearing carbon. Inspired by the work of Suzuki, Negishi, and Levy on the coupling of symmetrical boranes, − we reasoned that addition of a suitable electrophile would generate cation II by S E Ar. This was expected to trigger a 1,2-migration and following elimination would give aryl-coupled product III stereospecifically.…”

Section: Design Planmentioning

confidence: 99%

Development of Enantiospecific Coupling of Secondary and Tertiary Boronic Esters with Aromatic Compounds

et al. 2016

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The stereospecific cross-coupling of secondary boronic esters with sp2 electrophiles (Suzuki–Miyaura reaction) is a long-standing problem in synthesis, but progress has been achieved in specific cases using palladium catalysis. However, related couplings with tertiary boronic esters are not currently achievable. To address this general problem, we have focused on an alternative method exploiting the reactivity of a boronate complex formed between an aryl lithium and a boronic ester. We reasoned that subsequent addition of an oxidant or an electrophile would remove an electron from the aromatic ring or react in a Friedel–Crafts-type manner, respectively, generating a cationic species, which would trigger 1,2-migration of the boron substituent, creating the new C–C bond. Elimination (preceded by further oxidation in the former case) would result in rearomatization giving the coupled product stereospecifically. Initial work was examined with 2-furyllithium. Although the oxidants tested were unsuccessful, electrophiles, particularly NBS, enabled the coupling reaction to occur in good yield with a broad range of secondary and tertiary boronic esters, bearing different steric demands and functional groups (esters, azides, nitriles, alcohols, and ethers). The reaction also worked well with other electron-rich heteroaromatics and 6-membered ring aromatics provided they had donor groups in the meta position. Conditions were also found under which the B(pin)- moiety could be retained in the product, ortho to the boron substituent. This protocol, which created a new C(sp2)–C(sp3) and an adjacent C–B bond, was again applicable to a range of secondary and tertiary boronic esters. In all cases, the coupling reaction occurred with complete stereospecificity. Computational studies verified the competing processes involved and were in close agreement with the experimental observations.

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A novel regiospecific aryl ketone synthesis by the reaction of arylborate anions with acyl chlorides

Cited by 32 publications

References 0 publications

Stereospecific Couplings of Secondary and Tertiary Boronic Esters

Stereospecific Couplings of Secondary and Tertiary Boronic Esters

Direct Conversion of Carboxylic Acids to Alkyl Ketones

Development of Enantiospecific Coupling of Secondary and Tertiary Boronic Esters with Aromatic Compounds

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