Rhodium-catalyzed asymmetric synthesis of indanones: development of a new "axially chiral" bisphosphine ligand

A rhodium-catalyzed asymmetric isomerization of racemic alpha-arylpropargyl alcohols to beta-chiral indanones has been developed. High enantioselectivity has been realized by the use of a newly developed axially chiral bisphosphine ligand. This ligand is unique in the sense that its axial chirality is fixed to a single configuration upon complexation to a transition metal due to other chiral axes existing within the same molecule.     

Synthesis of chiral 3-substituted indanones via an enantioselective reductive-Heck reaction

An efficient intramolecular palladium-catalyzed, asymmetric reductive-Heck reaction has been developed, which allowed for the synthesis of either enantiomerically enriched 3-substituted indanones or alpha-exo-methylene indanones depending on the base used.     

Structure and Substituent Effects on Retention and Chiral Resolution of Ketones and Alcohols on Microcrystalline Cellulose Triacetate Plates

This paper reports a number of original thin layer chromatography enantioseparations of closely related ketones and alcohols such as tetralones, indanones, and benzhydrols carried out by elution with aqueous-alcoholic mixtures at different ratios. In order to investigate the structural and substituent effects on chiral recognition of microcrystalline cellulose triacetate, the results were compared with those obtained in previous papers for analogous compounds in similar experimental conditions. Even though the inclusion model of retention of analytes on this chiral stationary phase is confirmed, different and unexpected results were obtained for compounds having very favourable characteristics for resolution.     

A Facile Synthesis of Novel Dihydroindeno[1,2‐e][1,2,4]triazolo[3,4‐b][1,3,4]thiadiazines Using HTIB

The synthesis of a series of 21 novel 3‐alkyl/aryl‐7/9‐methyl‐10,10a‐dihydroindeno[1,2‐e][1,2,4]triazolo[3,4‐b][1,3,4]thiadiazines ( 4 ) has been achieved by the cyclocondensation between 4/6‐methyl‐2‐tosyloxy‐1‐indanones ( 2 ) and 3‐alkyl/aryl‐4‐amino‐5‐mercapto‐1,2,4‐s‐triazoles ( 3 ). 4/6‐Methyl‐2‐tosyloxy‐1‐indanones ( 2 ) were readily accessible through hypervalent iodine oxidation of 4/6‐methyl‐1‐indanones using [(hydroxy)tosyloxyiodo]benzene (HTIB, Koser's reagent) in acetonitrile.     

The synthesis of indanones related to combretastatin A-4 via microwave-assisted Nazarov cyclization of chalcones

A fast and efficient microwave-assisted synthesis of combretastatin A-4-like indanones has been developed. Microwave irradiation provides a useful alternative to traditional heating techniques to promote the TFA-catalyzed Nazarov cyclization of chalcones.     

Synthesis of indanones via solid-supported [2+2+2] cyclotrimerization

A new facile approach toward natural and unnatural indanones has been developed, featuring a solid-supported [2+2+2] cyclotrimerization as the key step. This strategy has been applied to the chemo- and regioselective assembly of indanone arrays and to the total synthesis of a recently isolated indanone marine natural product.     

Rhodium-catalyzed addition of arylzinc reagents to aryl alkynyl ketones: synthesis of beta,beta-disubstituted indanones

A rhodium-catalyzed addition of arylzinc reagents to aryl alkynyl ketones for the synthesis of highly substituted indanones has been developed. The key to success has proved to be a proper choice of the reaction system, which involves the employment of dppf as a ligand and 1,2-dichloroethane as a solvent.     

Carbopalladation of nitriles: synthesis of benzocyclic ketones and cyclopentenones via Pd-catalyzed cyclization of omega-(2-iodoaryl)alkanenitriles and related compounds

An efficient procedure for the synthesis of 2,2-disubstituted benzocyclic ketones by intramolecular carbopalladation of nitriles has been developed. The cyclization of substituted 3-(2-iodoaryl)propanenitriles affords indanones in high yields. The reaction is compatible with a wide variety of functional groups. This methodology has been extended to the synthesis of tetralones and cyclopentenones.     

Catalytic behavior of a magnesium oxide supported polysilazane-ruthenium complex for the oxidation of indene with molecular oxygen to indanones

A new magnesium oxide supported polysilazane ruthenium complex has been prepared and found to be capable of catalyzing the oxygenation of indene in 62.9% conversion to indanones without by-products under mild conditions, i.e. 1 atm oxygen and 80°C. The supported ruthenium complex was effective without need for a cocatalyst. Also, it can be reused several times without apparent loss of activity.     

The power of solvent in altering the course of photorearrangements

A clean bifurcation between two important photochemical reactions through competition of a triplet state Type II H-abstraction reaction with a photo-Favorskii rearrangement for (o/p)-hydroxy-o-methylphenacyl esters that depends on the water content of the solvent has been established. The switch from the anhydrous Type II pathway that yields indanones to the aqueous-dependent pathway producing benzofuranones occurs abruptly at low water concentrations (~8%). The surprisingly clean yields suggest that such reactions are synthetically promising.     

Transition metal catalyzed carboannulation of diazabicyclic alkenes with ambiphilic bifunctional reagents: a facile route towards functionalized indanones and indanols

Functionalized indanones are readily prepared in good to excellent yields by the Pd/Rh catalyzed carboannulation of bicyclic and tricyclic hydrazines with 2-iodobenzonitrile, 2-cyanophenylboronic acid and 2-formylphenylboronic acid. The reaction with 2-formylphenylboronic acid afforded 3,4-disubstituted cyclopentenes as minor product along with indanones under Rh catalyzed conditions, whereas indanols were obtained as the major product under Pd catalyzed conditions. The products obtained can be synthetically manipulated easily to pharmaceutically important molecules.     

Synthesis of Substituted 4‐Aroyl‐1‐indanone and 5‐Aroyl‐1‐tetralone

Several substituted 4‐aroyl‐1‐indanones 2 and 5‐aroyl‐1‐tetralones 3 were prepared in good yields from 1‐indanones 1 via a series of reasonable transformations.     

Syntheses of Substituted Indan 1 ones and Indenes

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Hydroacylation of 2-vinyl benzaldehyde systems: an efficient method for the synthesis of chiral 3-substituted indanones

Asymmetric rhodium-catalyzed hydroacylation has been utilized in the synthesis of 3-substituted indanones with high conversions and enantioselectivity. The hydroacylation reaction of 2-vinyl benzaldehyde had been previously reported to give a low yield of indanone and an unidentified product. We have identified this compound as a dimer of the starting material. Substitution at the alpha-position of the 2-vinyl benzaldehyde substrates blocks the competitive dimerization reaction and allows the reaction to proceed with yields generally greater than 90%. Utilization of BINAP as a chiral ligand results in good chemical yields and enantioselectivity greater than 95% in most cases.     

Application of the intramolecular isomerisation-aldolisation from allylic alcohols and allylic silyl ethers to the synthesis of indanones and indenones

A new access to indanones was discovered through a one-step nickel or iron-mediated transposition of 2-hydroxyisobenzofurans. Starting from the corresponding silylenol ethers, a new one-pot tandem isomerisation-Mukaiyama aldol process was also developed. These versatile strategies will be useful for the preparation of various types of indanones and indenones.     

Synthesis of fused 4,5-disubstituted indole ring systems by intramolecular friedel-crafts acylation of 4-substituted indoles

4-Substituted indoles containing a variety of electrophiles and N-substituents undergo Friedel-Crafts acylation to give exclusively the products of cyclization at the 5-position of indole. These indanones and tetralones have been scarcely prepared and are subunits in natural products and analogues of potential biological significance.     

A Convenient Method of Benzylic Oxidation with Pyridinium Chlorochromate

Oxidation of indans and tetralin derivatives to their corresponding indanones and tetralones is of considerable value i n organic synthesis and many methods have been reported for accomplishing this conversion. Traditionally these oxidations are performed with chromic acid in acetic acid and the yields in general are moderate. Recently Eisenbraun4 has studied indetail the benzylic oxidation with the Jones reagent and compared the selectivity and yield of oxidation with other chromium(V1) reagents like bipyridinim chlorochrmate, (BiPCC). It was found that there was no improvement in yield and in the case of BiPCC a molar ratio 16% 1 (oxidant: substrate) was employed to get     

Arynic condensation of ketone enolates—XIV: Condensation of aromatic α,β-unsaturated ketone enolates on arynes

Benzyne and 1-naphthyne (generated from the corresponding halogeno derivatives and the Complex Base NaNH₂-Bu^tONa) condense with α,β-unsaturated ketone enolates β-substituted by an aromatic ring and only enolisable in the α'-position, to lead to α-tetralones and/or indanones. The reaction path depends upon the nature of the ketone enolate and, less strongly, on the solvent. The reaction mechanism is discussed. These reactions constitute new simple and efficient syntheses of numerous α-tetralones and indanones.     

Pd‐Catalyzed Enantioselective Ring Opening/Cross‐Coupling and Cyclopropanation of Cyclobutanones

A palladium‐catalyzed enantioselective sequential ring‐opening/cross‐coupling of cyclobutanones is disclosed that provides chiral indanones bearing C3‐quaternary stereocenters. The reaction process involves palladium‐catalyzed nucleophilic addition of cyclobutanones and aryl halides, enantioselective β‐carbon elimination, and intermolecular trapping of a transient σ‐alkylpalladium complex with boronic acids. Alternatively, an intramolecular cyclopropanation is realized through C?H bond functionalization in the absence of external coupling reagents, affording chiral cyclopropane‐fused‐indanones in good yields and enantioselectivity.     

A Systematic Investigation of Long-Range Couplings in the 1H NMR Spectra of Dimeric Indanones

 During the synthesis of methyl substituted indanones by intramolecular cyclization of 3-phenyl-propionic acids, dimerization led to by-products which can be considered as dimeric indanones. The proton NMR spectra of these compounds exhibit pronounced scalar couplings over up to seven bonds. A series of structures of the above type were investigated, and their NMR spectroscopic behaviour is discussed.