Polysubstituted Indenes Research Articles

Straightforward Synthesis of Indenes by Gold-Catalyzed Intramolecular Hydroalkylation of Ynamides.

An original and straightforward entry to polysubstituted indenes from readily available ynamides is reported. Upon reaction with a N-heterocyclic carbene-gold complex under mild conditions, activated keteniminium ions are generated whose unique electrophilicity triggers a [1,5]-hydride shift and a subsequent cyclization. The presence of an endocyclic enamide in the densely functionalized resulting indenes was shown to be especially useful and versatile, offering a range of opportunities for their further postfunctionalization.

The intramolecular reaction of acetophenone N-tosylhydrazone and vinyl: Brønsted acid-promoted cationic cyclization toward polysubstituted indenes.

In the presence of TsNHNH2, a Brønsted acid-promoted intramolecular cyclization of o-(1-arylvinyl) acetophenone derivatives was developed, leading to polysubstituted indenes with complexity and diversity in moderate to excellent yields. In sharp contrast with either the radical or carbene involved cyclization of aldehydic N-tosylhydrazone with vinyl, a cationic cyclization pathway was involved, where N-tosylhydrazone served as an electrophile and alkylation reagent during this transformation.

TfOH/Fe(OTf)3 Cocatalyzed Reaction of Arylallenes with Alcohols for Structurally Diverse Indene Derivatives

AbstractThe indene moiety is an important unit because of its presence in many chemical catalysts, functional materials and biologically relevant molecules. Herein, we report a facile reaction of arylallenes with benzylic or allylic alcohols through TfOH/Fe(OTf)3 cocatalyzed cleavage of sp3 carbon‐oxygen. In the presence of 5 mol% TfOH and 5 mol% Fe(OTf)3, a range of arylallenes undergo carbocation initiated cyclization reaction with alkyl alcohols to give structurally diverse polysubstituted indenes in good to excellent yields. H2O is the sole byproduct that makes this transformation highly atom‐economic and environmentally benign.

Ferric chloride-catalyzed C–N bond cleavage for the cyclization of arylallenes leading to polysubstituted indenes

A range of arylallenes undergo carbocation-initiated cyclization reaction with N-benzylic and N-allylic sulfonamides in the presence of 10 mol% ferric chloride to give structurally diverse polysubstituted indenes in good yields with extremely high regioselectivity.

CuI-catalyzed tandem carbomagnesiation/carbonyl addition of Grignard reagents with acetylenic ketones: Convenient access to tetrasubstituted allylic alcohols

Highly functionalized tetrasubstituted allylic alcohols were prepared conveniently by CuI-catalyzed tandem carbomagnesiation/carbonyl addition of Grignard reagents with acetylenic ketones. The obtained allylic alcohols can be further transformed to polysubstituted indenes by intramolecular cyclization.

Synthesis of Substituted Indenes through Iron‐Catalyzed Annulation of Benzylic Alcohols with Alkynes

AbstractA convenient and efficient method for the synthesis of polysubstituted indenes has been developed by the iron(III) trichloride‐catalyzed tandem mono‐ and dibenzylation/cyclization reactions of benzylic alcohols with alkynes. This method is featured with the easily available starting materials, cheap catalyst, simple manipulation and mild conditions.

Synthesis of Substituted Indenes andcis-Stilbenoid Hydrocarbons via Palladium-Catalyzed Domino Reactions of Hindered Grignard Reagents with (E)-1,2-Dibromoethenes

Palladium-catalyzed domino reactions of (E)-1,2-dibromoethenes with hindered Grignard reagents based on carbopalladation, palladium-catalyzed cross-coupling, and C-H activation are described. These domino reactions could be influenced by the ligand, reaction temperature, nucleophilicity of Grignard reagents, and steric hindrance of the substrates. Our study provides an efficient access to some useful polysubstituted indenes and cis-substituted stilbenes, and may be useful for the development of other cross-coupling and C-H activation-based tandem/domino reactions.

Two Palladium-Catalyzed Domino Reactions from One Set of Substrates/Reagents: Efficient Synthesis of Substituted Indenes and cis-Stilbenoid Hydrocarbons from the Same Internal Alkynes and Hindered Grignard Reagents

Two types of domino reactions from the same internal alkynes and hindered Grignard reagents based on carbopalladation, Pd-catalyzed cross-coupling reaction, and a C-H activation strategy are described. The realization of these domino reactions relied on the control of the use of the ligand and the reaction temperature. Our study provides efficient access to useful polysubstituted indenes and cis-substituted stilbenes and may offer a new means of development of tandem/domino reactions in a more efficient way. [reaction: see text].

Corrigendum to “Intramolecular cyclization and disilylation of 1,1-dicyano-2,2-diarylethenes promoted by samarium/TMSCl in DMF: a new approach to the syntheses of polysubstituted indenes”[Tetrahedron Lett. 45 (2004) 4571

Corrigendum to “Intramolecular cyclization and disilylation of 1,1-dicyano-2,2-diarylethenes promoted by samarium/TMSCl in DMF: a new approach to the syntheses of polysubstituted indenes”[Tetrahedron Lett. 45 (2004) 4571

Intramolecular Cyclization and Disilylation of 1,1‐Dicyano‐2,2‐diarylethenes Promoted by Samarium/TMSCl in DMF: A New Approach to the Syntheses of Polysubstituted Indenes.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Intramolecular cyclization and disilylation of 1,1-dicyano-2,2-diarylethenes promoted by samarium/TMSCl in DMF: a new approach to the syntheses of polysubstituted indenes

Promoted by samarium metal in DMF and in the presence of TMSCl, 1,1-diaryl-2,2-dicyanoethylenes undergo an unexpected kind of reductive cyclization, thus affording a new approach to the construction of indene core. Simultaneously, disilylation occurred at the amino moiety resulting from the reduction of the cyano group.

Intramolecular cyclization and disilylation of 1,1-dicyano-2,2-diarylethenes promoted by samarium/TMSCl in DMF: a new approach to the syntheses of polysubstituted indenes

Intramolecular cyclization and disilylation of 1,1-dicyano-2,2-diarylethenes promoted by samarium/TMSCl in DMF: a new approach to the syntheses of polysubstituted indenes

Intramolecular Substitution Reaction of Alkylidene-Lithium Carbenoids: Regioselective Synthesis of Indenes

Intramolecular substitution reaction of geminal dibromo alkenes proceeds to afford indenes, dihydronaphthalenes, dihydrofurans, and dihydropyran via in situ generated lithium alkylidene carbenoids, which have a carbon or oxygen nucleophilic moiety. This reaction provides a regioselective method for the preparation of polysubstituted indenes.