Oxidative Coupling the Toluic Acid Dianion System

Belletire, J. L.; Spletzer, E. G.

doi:10.1080/00397918608078776

Cited by 16 publications

(4 citation statements)

References 10 publications

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“…In 1968, Kauffmann reported the first example of an oxidative dimerization of a ketone enolate, namely acetophenone, using copper(I) salts, albiet in modest yields. 19 29,33 which show the versatility of this coupling reaction in the formation of a wide variety of dimerized compounds. Several reports exist that elicit the coupling of other stabilized anions, such as phosphine oxides, 34 sulfoxides/sulfones, 34 and methylpyridines 36b under similar conditions.…”

Section: Background and Historical Contextmentioning

confidence: 90%

“…Epoxide 41 is obtained in acceptable yield, even though multiple side reactions could be envisioned in the presence of this reactive moiety. Quaternary centers can be formed in moderate (benzylcarvone 40) to good (tricycle 32 and lactone 43) yields and coupling can even occur at hindered neopentyl centers such as that of isophorone (33). The reaction is amenable to asymmetric synthesis with either the Evans (27) or Oppolzer (28-31) chiral auxiliaries in good to excellent diastereoselectivities and yields.…”

Section: Scopementioning

confidence: 99%

“…He also described the heterocoupling of two different ketone enolates, which required 3 equiv or more of one of the coupling partners to furnish acceptable yields of the heterocoupled product. Many reports have appeared that use a wide variety of oxidants to effect the couplings, including copper salts, 18b,c,− ,23c,d,24m,,26d iron salts, 18d,,37d,e iodine, 18a,c,23d,,28b,,37a-c N -iodosuccinimide, hypervalent iodine-based reagents, silver salts, 18b, titanium salts, 26d, potassium permanganate, direct electrochemical oxidation, 18a, short chain alkyl polyhalides, and bromine. , A few studies involving the dimerization of enolates conjugated throughout an aromatic system have been reported, , which show the versatility of this coupling reaction in the formation of a wide variety of dimerized compounds. Several reports exist that elicit the coupling of other stabilized anions, such as phosphine oxides, sulfoxides/sulfones, and methylpyridines 36b undersimilar conditions.…”

Section: Background and Historical Contextmentioning

confidence: 99%

“…(50) See Supporting Information for a detailed general procedure. (33). The reaction is amenable to asymmetric synthesis with either the Evans (27) or Oppolzer (28-31) chiral auxiliaries in good to excellent diastereoselectivities and yields.…”

Section: Scopementioning

confidence: 99%

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Scope and Mechanism of Direct Indole and Pyrrole Couplings Adjacent to Carbonyl Compounds: Total Synthesis of Acremoauxin A and Oxazinin 3

et al. 2007

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Full details are provided for a recently invented method to couple indoles and pyrroles to carbonyl compounds. The reaction is ideally suited for structurally complex substrates and exhibits high levels of chemoselectivity (functional group tolerability), regioselectivity (coupling occurs exclusively at C-3 of indole or C-2 of pyrrole), stereoselectivity (substrate control), and practicality (amenable to scale-up). In addition, quaternary stereocenters are easily and predictably generated. The reaction has been applied to a number of synthetic problems including total syntheses of members of the hapalindole family of natural products, ketorolac, acremoauxin A, and oxazinin 3. Mechanistically, this coupling protocol appears to operate by a single electron transfer process requiring generation of an electron-deficient radical adjacent to a carbonyl which is then intercepted by an indole or pyrrole anion.

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Section: Background and Historical Contextmentioning

confidence: 90%

Section: Scopementioning

confidence: 99%

Section: Background and Historical Contextmentioning

confidence: 99%

Section: Scopementioning

confidence: 99%

See 2 more Smart Citations

Scope and Mechanism of Direct Indole and Pyrrole Couplings Adjacent to Carbonyl Compounds: Total Synthesis of Acremoauxin A and Oxazinin 3

et al. 2007

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Directed metallation of aromatic compounds

Clayden¹

2004

PATAI'S Chemistry of Functional Groups

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Lateral Lithiation Reactions Promoted by Heteroatomic Substituents

Clark¹,

Jahangir²

1995

Organic Reactions

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Heteroatom‐facilitated lithiation reactions have assumed an increasingly important role in the elaboration of carbocyclic aromatic and heteroaromatic systems in the 40 years subsequent to the seminal review on metalation with organolithium reagents by Gilman and Morton. Of particular note has been the development of methodology for the lateral lithiation of alkyl‐substituted aromatic systems promoted by an extensive array of heteroatomic substituents. These lithiations involve deprotonation at a benzylic (side chain) position that is lateral to, or flanked by, a heteroatom‐containing substituent (G); this substituent facilitates lithiation relative to the parent system in which G is not present. The derived lithiated species have great synthetic utility for functionalization of benzylic sites, for chain extensions, and for the synthesis of fused carbocyclic and heterocyclic systems via annelation processes. This chapter summarizes the significant amount of work reported on heteroatom‐facilitated lateral lithiations and the synthetic applications thereof. The survey covers the substituents that promote these reactions, and the methods of formation, stability, reactivity, and synthetic utility of the lithiated species. Coverage is limited to examples in which the R 1 group in the representative equation is hydrogen (toluene derivatives), alkyl, or aryl. Examples that would be better classified as alpha ‐lithiations are not covered, for example, where R 1 is an anion‐stabilizing group such as cyano, carboxy, and so on. Rare examples of lithiations of alkyl groups that are meta or para to the facilitating group G are included in the chapter, although these are not, strictly speaking, lateral lithiations. Also included are a limited number of older lateral metalations that were originally effected with sodium or potassium bases but would now be more conveniently carried out with lithium dialkylamide bases. The aromatic nucleus may be carbocyclic or heterocyclic, but lateral lithiations of heterocycles lacking the heteroatomic substituent are not covered. For example, lithiation of nicotinamides (Eq. 2) are included; however, lithiations of picolines, and other heterocyclic systems, are considered beyond the scope of this chapter. The relationship of lateral lithiation reactions to heteroatom‐facilitated ortho lithiations is obvious and the two fields have developed, for the most part, in concert. With several notable exceptions, the same heteroatomic substituents (G) promote both types of lithiations. A number of reviews cover various aspects of ortho lithiation reactions, including the comprehensive chapter in Organic Reactions by Gschwend and Rodriguez that surveyed the literature to 1979. In the present chapter, the relationship of lateral lithiation and ortho lithiation reactions is discussed within the contexts of mechanism, reactivity, and synthetic utility. In addition, the sequential use of these two lithiation processes for the synthesis of complex aromatic and heteroaromatic systems is covered.

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Oxidative Coupling the Toluic Acid Dianion System

Cited by 16 publications

References 10 publications

Scope and Mechanism of Direct Indole and Pyrrole Couplings Adjacent to Carbonyl Compounds: Total Synthesis of Acremoauxin A and Oxazinin 3

Scope and Mechanism of Direct Indole and Pyrrole Couplings Adjacent to Carbonyl Compounds: Total Synthesis of Acremoauxin A and Oxazinin 3

Directed metallation of aromatic compounds

Lateral Lithiation Reactions Promoted by Heteroatomic Substituents

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