Aromatic benzene compounds from acyclic precursors

Bamfield, Peter; Gordon, P. F.

doi:10.1039/cs9841300441

Cited by 78 publications

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“…The preparation of phenols from ketone precursors have been explored previously ( 8-16 ). Condensation reactions of acyclic ketones, for example, with β-ketoaldehydes or β-diketones, enab le direct access to substituted phenols ( 8 ), but low product yields, limited access to starting materials and/or formation of isomeric products have restricted the utility of these procedures.…”

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confidence: 99%

“…Condensation reactions of acyclic ketones, for example, with β-ketoaldehydes or β-diketones, enab le direct access to substituted phenols ( 8 ), but low product yields, limited access to starting materials and/or formation of isomeric products have restricted the utility of these procedures. Methods for formation of phenols via dehydrogenation of cyclohexenones have been pursued ( 8-13 ), but reactions of this type typically employ undesirable stoichiometric reagents, such as DDQ (2,3-dichloro-5,6-dicyano-1,4-benzoquinone) ( 17 ), utilize stepwise procedures, such as bromination/dehydrobromination, or require harsh reaction conditions (≥ 200 °C) that limit functional group compatibility. In contrast, no effective methods for dehydrogenation of substituted cyclohexanones exist, with relevant precedents almost exclusively limited to reactions of unsubstituted cyclohexanone and yields of ≤ 30 % (mostly < 5%) ( 12-16 ).…”

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Palladium-Catalyzed Aerobic Dehydrogenation of Substituted Cyclohexanones to Phenols

Izawa

Pun

Stahl

2011

Science

423

198

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Aromatic molecules are key constituents of many pharmaceuticals, electronic materials and commodity plastics. The utility of these molecules directly reflects the identity and pattern of substituents on the aromatic ring. Here, we report the discovery of a palladium(II) catalyst system, incorporating an unconventional ortho-dimethylaminopyridine ligand, for the conversion of substituted cyclohexanones to the corresponding phenols. The reaction proceeds via successive dehydrogenation of two saturated carbon-carbon bonds of the six-membered ring and uses molecular oxygen as the hydrogen acceptor. This reactivity demonstrates a versatile and efficient strategy for the synthesis of substituted aromatic molecules with fundamentally different selectivity constraints from the numerous existing synthetic methods that rely on substitution of a pre-existing aromatic ring.

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confidence: 99%

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confidence: 99%

Palladium-Catalyzed Aerobic Dehydrogenation of Substituted Cyclohexanones to Phenols

Izawa

Pun

Stahl

2011

Science

423

198

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“…The Danheiser synthesis is based on the annulation strategy of heterosubstituted acetylenes and cyclobutenones for a highly substituted arene system . The forward synthesis of the natural product was initiated with the synthesis of fragments 70 and 71 .…”

Section: Reports Of the Total Synthesis Of Mycophenolic Acidmentioning

confidence: 99%

“…The Danheiser synthesis [53] is based on the annulation strategy of heterosubstituted acetylenes and cyclobutenones for a highly substituted arene system. [54] The forward synthesis of the natural product was initiated with the synthesis of fragments 70 and 71. The NaBH 4 reduction of the known aldehyde 49 [55] produced the expected alcohol 66; it was protected as the tert-butyldimethylsilyl ether 67 with treatment of tBuMeSiCI and Et 3 N in the presence of a catalytic amount of 4-(dimethylamino)pyridine (DMAP).…”

Section: R L Danheiser (1986)mentioning

confidence: 99%

Mycophenolic Acid: Biogenesis, Compound Isolation, Biological Activity, and Historical Advances in Total Synthesis

et al. 2019

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The 6‐alkyl‐2,4‐dihydroxybenzoate moiety known commonly as resorcylate occurs widely as a building block in various fused cyclic systems of bioactive natural products and analogues. Among these many isolated active molecules, mycophenolic acid (MPA) was one of the most studied for its structural features and its potential biological activity. This perspective article portrays the unique biosynthetic interrelationships of polyketide formations in to resorcylates, which are implemented by recent biomimetic/chemical synthetic investigations of the natural product target. The resorcylate, MPA have remained as interesting targets for total synthesis in many laboratories worldwide. There are 13 syntheses reported for MPA to date (Scifinder search). The synthetic strategies for this potential lead compound was an evolution of various methods from generating the highly‐substituted aromatic system via employing simple and commercially available materials to the catalytic methods employed which always involve linear sequences; convergent approaches to the most important protecting group‐free syntheses are also briefly documented in this critical review. This natural product has been the subject of considerable synthetic study. Most reported total syntheses employ 6‐alkyl‐2,4‐hydroxybenzoic acids (lactones) as intermediates and proceed via stepwise derivatization to introduce other functionalities.

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“…The response is, let's buy it [6]. Since, also invariably, this fails, the SciFinder TM or equivalent data base produces (hopefully) a number of hits based on familiar tactics which include (Scheme 1): E þ substitution [2], Nu À substitution (including S RN 1 processes) [3], cycloaddition (usually Diels-Alder) [7], and de novo ring construction [8], which are familiar but not always fully appreciated. While also not accepted pedagogically, efforts by numerous groups over the past 25 years have added the Directed ortho Metalation (DoM) reaction to the armamentarium of the synthetic chemist as a general, regioselective, and effective strategy for the rational construction of polysubstituted aromatic and heteroaromatic substances [9].…”

Section: Introductionmentioning

confidence: 99%

The Directed ortho Metalation Reaction – A Point of Departure for New Synthetic Aromatic Chemistry

Hartung

Snieckus

2002

Modern Arene Chemistry

159

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After a brief allusion to the current status of synthetic aromatic chemistry, a tour based on the Directed ortho Metalation (DoM) strategy is provided with selections from recent literature which highlight a) the use of DoM for the regiospecific preparation of polysubstituted aromatics and heteroaromatics; b) the valuable symbiosis of DoM with transition metal catalyzed AraAr cross-coupling protocols; c) the extension of DoM to the Directed remote Metalation (DreM) concept in biaryls, which provides methodologies for the construction of condensed aromatics (fluorenones, phenanthrols) and heterocyclics (thioxanthones, xanthones, acridones, dibenzphosphorinones, dibenzthiepinone dioxides, dibenzoxepinones, dibenzazepinones, dibenzphosphinones); and d) the evolving links of DoM to other modern methodologies with a note on the DoM-Grubbs ring-closing metathesis connection. The presentation is solely methodologically rather than total synthesis oriented; dependable directed metalation groups (DMGs ¼ CONR 2 , OCONR 2 , SONR 2 , NHBoc), new and renewed, are emphasized; p-excessive (furan, thiophene, indole) and p-deficient (pyridine) heterocycle HetDoM chemistry is delineated. While definitely not comprehensive, this account attempts to give a flavor of current anionic aromatic chemistry in synthesis. 10.1Scheme 1. Synthetic approaches to substituted aromatics. 10.2 The DoM Reaction as a Methodological Tool 331 Scheme 3. DoM chemistry generalizations. 10.2 The DoM Reaction as a Methodological Tool 333 Scheme 5. The N-cumyl sulfonamide DMG. Scheme 6. The N-cumyl carbamate DMG. 10.2 The DoM Reaction as a Methodological Tool 335 Scheme 9. The di-tert-butyl phosphine oxide DMG. 10.3 Heteroaromatic Directed ortho Metalation (HetDoM) in Methodological Practice 337

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Aromatic benzene compounds from acyclic precursors

Abstract: In this review heterocycles will therefore be considered as masked acyclic compounds.

Cited by 78 publications

References 0 publications

Palladium-Catalyzed Aerobic Dehydrogenation of Substituted Cyclohexanones to Phenols

Palladium-Catalyzed Aerobic Dehydrogenation of Substituted Cyclohexanones to Phenols

Mycophenolic Acid: Biogenesis, Compound Isolation, Biological Activity, and Historical Advances in Total Synthesis

The Directed ortho Metalation Reaction – A Point of Departure for New Synthetic Aromatic Chemistry

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