Polysubstituted Benzene Derivatives Research Articles

Synthesis of 1,2,4,5-tetra-substituted benzenes via copper-catalyzed dimerization of γ,δ-unsaturated ketones.

An efficient cyclization for the synthesis of 1,2,4,5-tetra-substituted benzenes via copper catalyzed dimerization of γ,δ-unsaturated ketones has been described. This one-pot procedure employs the γ,δ-unsaturated ketones as the sole substrate with multiple C-C bond formation. This protocol features broad substrate scope and provides a facile and robust method to construct polysubstituted benzene derivatives under mild conditions.

Regioselective Synthesis of Tetrasubstituted Benzenes via Co-Catalyzed Cycloaddition of Alkynyl Ketones and 2-Acetylpyridines

A Co(II)-catalyzed cycloaddition reaction of alkynyl ketones and 2-acetylpyridines using 2,2'-bipyridine as the ligand has been developed. These reactions have been realized through Co-catalyzed reductive coupling of two molecules of 2-acetylpyridine followed by regioselective insertion of the alkynone. It is the first example of regioselective cyclotrimerization of one molecule of alkyne and two molecules of monoketone to polysubstituted benzene derivatives in good to excellent yields. A mechanism involving the formation of a cobaltacyclopentane via homocoupling of 2-acetylpyridines is proposed, and it is supported by the DFT calculations.

Synthesis of Benzofused N-Heterocycles via Rh(III)-Catalyzed Direct Benzannulation with 1,3-Dienes

Benzofused nitrogen heterocycles are prevalent as key core structural motifs in functional molecules. Major syntheses of benzofused nitrogen heterocycles focus on construction of the heterocyclic ring starting from (poly)substituted benzene derivatives. Given that polysubstituted benzene derivatives are not always easily available, the flexibility of these methods may be problematic. The direct benzannulation reactions of simple N-heterocycles thus provide a complementary and valuable strategy. However, this approach has been far less explored, especially when nonprefunctionalized N-heterocycles are used as starting materials. In recent years, the metal-catalyzed direct functionalization of an inert C–H bond has become a powerful tool to construct (hetero)aromatics. In the C–H benzannulation reactions, alkynes, activated alkenes, enaldiazo compounds, and biaryl compounds were previously utilized as efficient coupling partners. Reported herein is a de novo synthesis of a benzene ring through the rhodium-ca...

Volatiles from the hypoxylaceous fungi Hypoxylon griseobrunneum and Hypoxylon macrocarpum.

The volatiles emitted by the ascomycetes Hypoxylon griseobrunneum and Hypoxylon macrocarpum (Hypoxylaceae, Xylariales) were collected by use of a closed-loop stripping apparatus (CLSA) and analysed by GC–MS. The main compound class of both species were polysubstituted benzene derivatives. Their structures could only be unambiguously determined by comparison to all isomers with different substitution patterns. The substitution pattern of the main compound from H. griseobrunneum, the new natural product 2,4,5-trimethylanisole, was explainable by a polyketide biosynthesis mechanism that was supported by a feeding experiment with (methyl-2H3)methionine.

Efficient regioselective approach for polysubstituted benzene derivatives by intermolecular [2+2+2] cyclotrimerization of alkynes

We present an important opinion about the electron effect of the intermolecular cyclcotrimerization of unsymmetrical diaryalkynes in the presence of Co2(CO)8 on the production of corresponding 1,2,4-regioisomer or 1,3,5-regioisomer derivatives with excellent yields and high regioselectivity.

Chemo- and Regioselective Rhodium(I)-Catalyzed [2+2+2] Cycloaddition of Allenynes with Alkynes.

A highly chemo- and regioselective partially intramolecular rhodium(I)-catalyzed [2+2+2] cycloaddition of allenynes with alkynes is described. A range of diverse polysubstituted benzene derivatives could be synthesized in good to excellent yields, in which the allenynes served as synthetic equivalent to the diynes. A high regioselectivity could be observed when allenynes were treated with unsymmetrical alkynes.

Transition-Metal-Free Multicomponent Benzannulation Reactions for the Construction of Polysubstituted Benzene Derivatives.

A transition-metal-free multicomponent benzannulation reaction was developed from readily available ketones, nitro-olefins, and diester acetylenedicarboxylate. This approach provides a straightforward and efficient way to construct polysubstituted benzene derivatives under mild conditions in high yields.

Platinum(IV)‐Catalyzed Synthesis of Unsymmetrical Polysubstituted Benzenes via Intramolecular Cycloaromatization Reaction

AbstractA one‐pot synthesis of polysubstituted benzene derivatives was achieved via a platinum(IV)‐catalyzed intramolecular cycloaromatization reaction. The reaction proceeds via a tandem skeletal rearrangment, dehydration and double bond isomerization, which proved to be very useful for the syntheses of a range of interesting polyalkyl‐substituted benzenes.magnified image

ChemInform Abstract: Reactions of Enaminones and Related Compounds with N,N‐Dimethylacetamide Dimethyl Acetal. A Simple One‐Pot Metal‐Free Synthesis of Polysubstituted Benzene Derivatives.

Abstract Herein a simple one-pot metal-free synthesis of alkyl-, aryl-, heteroaryl- and alkoxycarbonyl substituted 1,3-bis(dimethylamino)benzene derivatives is described. The products were prepared from the corresponding methyl ketones or compounds with an α-methylene group in regard to the carbonyl group, using N,N-dimethylacetamide dimethyl acetal (DMADMA) as the reagent.

ChemInform Abstract: Synthesis of Poly‐Substituted Benzene Derivatives via [3 + 3] Annulation Protocol from Morita—Baylis—Hillman Adducts and Glutaconates.

AbstractTitle reaction leads to various polysubstituted benzene derivatives bearing 1,3‐dicarboxylate groups of type (III) or (V).

Reactions of enaminones and related compounds with N,N-dimethylacetamide dimethyl acetal. A simple one-pot metal-free synthesis of polysubstituted benzene derivatives

Herein a simple one-pot metal-free synthesis of alkyl-, aryl-, heteroaryl- and alkoxycarbonyl substituted 1,3-bis(dimethylamino)benzene derivatives is described. The products were prepared from the corresponding methyl ketones or compounds with an α-methylene group in regard to the carbonyl group, using N,N-dimethylacetamide dimethyl acetal (DMADMA) as the reagent.

Synthesis of Poly-Substituted Benzene Derivatives via [3+3] Annulation Protocol from Morita-Baylis-Hillman Adducts and Glutaconates

Morita-Baylis-Hillman (MBH) adducts 1 have been used for the synthesis of various aromatic compounds including poly-substituted benzenes 2 and phenols. 3 The reaction of MBH adduct and 1,3-dimethylacetone dicarboxylate has been used for the synthesis of poly-substituted phenols bearing 2,6-dicarboxylates via the [3+3] annulation protocol (vide infra, Scheme 1). 3a 1,3-Dimethylacetone dicarboxylate served a three-carbon unit with 1,3-dicarboxylates and 2keto functionality in the reaction. The corresponding polysubstituted benzene 3a has been synthesized in low yield (23%) 2a by DBU-mediated dehydrogenation of the cyclohexene intermediate which was prepared from MBH adduct and diethyl malonate (vide infra, Scheme 1). 4 Glutaconates have been used in organic synthesis in order to introduce a three-carbon unit bearing two carboxylates at the 1,3-position. 5,6 In these respects, we presumed that the reaction of MBH adduct and diethyl glutaconate could be used for the preparation of poly-substituted benzene derivatives bearing 1,3-dicarboxylates such as 3a, as shown in Scheme 1. At the outset of our experiment, the reaction of MBH bromide 1a and diethyl glutaconate (2a) was examined in CH3CN in the presence of Cs2CO3 at 50 o C for 2 h. To our delight, desired product 3a was obtained in moderate yield (61%). 7 The nucleophilic substitution of 1a with the anion of 2a would produce a resonance-stabilized carbanion intermediate I, 8 and the following cyclization, dehydration and a base-catalyzed 1,3-H shift produced 3a via an overall [3+3] annulation approach, as shown in Scheme 2. The reaction in refluxing CH3CN gave a similar yield of 3a (60%). After some trials, we found that the reaction in DMF at 90 o C produced 3a in good yield (72%) in short time (1 h), and we

ChemInform Abstract: Electrophilic Cyclization of 1,5‐Enynes.

AbstractIodonium‐induced cyclization of enynes with NIS provides access towards polysubstituted benzene derivatives in high yields.

ChemInform Abstract: Rh(I)‐Catalyzed Formal [2 + 2 + 2] Cycloadditions of 1,6‐Diynes with Potassium (Z)‐(2‐Bromovinyl)trifluoroborate: A New Strategy and a Facile Entry to Polysubstituted Benzene Derivatives.

ChemInform Abstract: Rh(I)‐Catalyzed Formal [2 + 2 + 2] Cycloadditions of 1,6‐Diynes with Potassium (Z)‐(2‐Bromovinyl)trifluoroborate: A New Strategy and a Facile Entry to Polysubstituted Benzene Derivatives.

ChemInform Abstract: One‐Step Synthesis of Polysubstituted Benzene Derivatives by Multicomponent Cyclization of α‐Bromoacetate, Malononitrile and Aromatic Aldehydes.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

One-step synthesis of polysubstituted benzene derivatives by multi-component cyclization of α-bromoacetate, malononitrile and aromatic aldehydes

Polysubstituted benzene derivatives with an unprecedented substitution pattern are produced in a novel one-pot multi-component cyclization reaction from pyridine, ethyl alpha-bromoacetate, malononitrile and aromatic aldehyde in refluxing acetonitrile.

Efficient Method for the Synthesis of Polysubstituted Benzenes by One-Pot Tandem Reaction of Vinyl Malononitriles with Nitroolefins

The one-pot synthesis of polysubstituted benzene derivatives was achieved via vinylogous Michael addition of vinyl malononitriles and nitroolefins as the key step and a sequential tandem reaction. A series of complex aryl compounds such as biphenyls and terphenyls can be obtained with satisfactory yields.

Regioselective synthesis of pentasubstituted benzene derivatives: TBAF as an effective catalyst for the sequential Michael addition-intramolecular aldolization

Polysubstituted benzene derivatives were synthesized starting from the Baylis–Hillman adducts via the sequential introduction of primary nitroalkane at the primary position, Michael addition to β-branched Michael acceptor, aldol condensation, elimination of nitrous acid, and the final aromatization process.

Iridium Complex‐Catalyzed [2 + 2 + 2] Cycloaddition of α,ω‐Diynes with Monoynes and Monoenes.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

From Allene to Allene: A Palladium‐Catalyzed Approach to β‐Allenyl Butenolides and Their Application to the Synthesis of Polysubstituted Benzene Derivatives.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.