Diphenylindane-based proteomimetics reproduce the projection of the i, i+3, i+4, and i+7 residues on an alpha-helix

[structure: see text] The design of a nonpeptidic scaffold based on 4,7-diphenyl-1,6-disubstituted indanes mimicking i, i+3, i+4, and i+7 residues of an alpha-helix has been described, and its synthesis has been accomplished. This strategy makes general approaches possible to helix mimetic scaffolds that could be targeted to different proteins by changing the nature of the substituents.     

An Unusual C[dbnd]C Bond Cleavage with Chromium VI Reagents: Oxidation of Primary Alcohols to Ketones

Oxidation of 1-hydroxymethyl indanes and 1-hydroxymethyltetralins with PDC or PCC in methylene chloride affords 1-indanones and 1-tetralones.     

Hypervalent iodine-mediated regioselective cyclization of acetylenic malonates: facile synthesis of 1-diiodomethylene indane and cyclopentane derivatives

A facile synthesis of potentially useful 1-diiodomethylene indanes and cyclopentanes from the regioselective cyclization of acetylenic malonates with the combination of iodosobenzene with tetrabutylammonium iodide in 2,2,2-trifluoroethanol is reported.     

Palladium‐Catalyzed Alkylation with Alkyl Halides by C(sp3)−H Activation

Utilizing halogens as traceless directing goups represents an attractive strategy for C−H functionalization. A two C−H alkylation system, initiated by the oxidative addition of organohalides to Pd⁰, has been developed. The first reaction involves an intermolecular alkylation of palladacycles to form C(sp³)−C(sp²) bonds followed by C(sp²)−H activation/cyclization to deliver alkylated benzocyclobutenes as the final products. In the second reaction, two C−C bonds are formed by the reaction of palladacycles with CH₂Br₂, and provides a facile and efficient method for the synthesis of indanes. The alkylated benzocyclobutene products can be transformed into tricyclic hyrocarbons, and the indane derivatives are essential structural motifs in bioactive and odorant molecules.     

Détermination de la structure et de la stéréochimie de dehydroindanes trisubstitués par R.M.M. bidimensionnelle.

The structure elucidation of trisubstituted indanes by 2-D N.M.R. techniques is described and is used to determine the mechanism of their formation.     

Carbene‐Catalyzed Desymmetrization and Direct Construction of Arenes with All‐Carbon Quaternary Chiral Center

Multisubstituted arenes such as indanes with attached all‐carbon quaternary centers are unique scaffolds in synthetic functional molecules and sophisticated natural products. A key challenge in preparing such molecules lies in the enantioselective installation of the quaternary carbon centers. Conventional methods in this direction include asymmetric substitution reactions and substrate‐controlled cyclization reactions. These reactions lead to poor stereoselectivities and/or require long and tedious synthetic steps. Disclosed here is a one‐step organic catalytic strategy for enantioselective access to this class of molecules. The reaction involves an N‐heterocyclic carbene catalyzed process for direct benzene construction, indane formation, remote‐carbon desymmetrization, and excellent chirality control. This approach will enable the concise synthesis of arene‐containing molecules, including those with complex structures and challenging chiral centers.     

Reaction of 2-(1-methyl-2-butenyl)anilines with polyphosphoric acid

Conclusions Cyclization of 2-(1-methyl-2-butenyl)anilines in polyphosphoric acid proceeds with isomerization of the side chain and leads to indolines and indanes in high yields.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 839–842, April, 1985.     

The homologous tert-amino effect: a route to fused 2-benzazepine derivatives

2-Cyano- and 2-carbethoxy-3-[2-(pyrrolidin-1-ylmethyl)phenyl]acrylonitriles were prepared through either amination of appropriate 3-[2-(bromomethyl)phenyl]acrylonitriles with pyrrolidine or condensation of 2-(pyrrolidin-1-ylmethyl)benzaldehyde with malononitrile and ethyl cyanoacetate. These acrylonitrile derivatives were shown to undergo easy mutual interconversion with 1-(pyrrolidin-1-yl)indane-2-carbonitriles driven by solvent polarity. Upon heating at 140-150 °C both acrylonitrile and indane derivatives were found to give 2,3,5,10,11,11a-hexahydro-1H-pyrrolo[1,2-b][2]benzazepine-11-carbonitriles. All transformations observed were rationalized in the terms of reactions related to the tert-amino effect. Furthermore, the corresponding piperidin-1-yl and azepan-1-yl analogs of the above acrylonitriles and indanes were obtained similarly. By analogy their heating afforded 1,2,3,4,6,11,12,12a-octahydropyrido[1,2-b][2]benzazepine-12-carbonitriles and 7,8,9,10,11,11a, 12,13-octahydro-5H-azepino[1,2-b][2]benzazepine-12-carbonitriles.     

Nickel-catalyzed asymmetric reductive aryl-allylation of unactivated alkenes

Herein we report a nickel-catalyzed asymmetric reductive aryl-allylation of aryl iodide-tethered unactivated alkenes, wherein both acyclic allyl carbonates and cyclic vinyl ethylene carbonates can serve as the coupling partners. Furthermore, the direct use of allylic alcohols as the electrophilic allyl source in this reaction is also viable in the presence of BOC anhydride. Remarkably, this reaction proceeds with high linear/branched-, E/Z- and enantio-selectivity, allowing the synthesis of various chiral indanes and dihydrobenzofurans (50 examples) containing a homoallyl-substituted quaternary stereocenter with high optical purity (90–98% ee). In this reductive reaction, the use of pregenerated organometallics can be circumvented, giving this process good functionality tolerance and high step-economy.

A nickel-catalyzed reductive asymmetric aryl-allylation of tethered unactivated alkenes has been developed, providing diverse benzene-annulated cyclic compounds bearing a quaternary stereocenter with high regio-, E/Z- and enantio-selectivity.     

Ionic hydrogenation of 1,3-indanedione derivatives

Conclusions The ionic hydrogenation of 1,3-indanedione and its 2-monosubstituted and 2,2-disubstituted derivatives to indanes was realized with triethylsilane in trifluoroacetic acid. Unsubstituted and 2-monosubstituted 1,3-indanediones undergo catalytic ionic hydrogenation.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 2084–2087, September, 1981.     

Gold(I)-Catalyzed Intramolecular C(sp3)−H Insertion by Decarbenation of Cycloheptatrienes

A novel synthesis of indanes and dihydronaphtalenes based on the intramolecular insertion into C(sp³)−H bonds of gold(I) carbenes generated by retro-Buchner reaction (decarbenation) has been developed. Deuterium-labeling and kinetic isotope effect experiments, DFT calculations, and generation of the proposed carbene intermediate from a well-characterized gold(I) carbenoid support the involvement of a three-center concerted mechanism for the C(sp³)−H functionalization process.     

Scope of the formal [3+2] cycloaddition for the synthesis of five-membered ring of functionalized indanes

We report our research about the synthesis of functionalized indanes in the pentagonal ring by a formal [3+2] cycloaddition using benzhydrols and styrene derivatives with electron-withdrawing groups joined to C-β, such as carboxyl, carboxymethyl, carbonyl of ketones, and nitro groups. We also report the configurational assignment of the indanic structures synthesized using several experiments of NMR.     

Palladium-catalysed heteroannulation of [60]fullerene with N-benzyl sulfonamides and subsequent functionalisation

The palladium-catalysed heteroannulation of [60]fullerene with various N-benzyl sulfonamides via C-H bond activation affords [60]fullerene-fused tetrahydroisoquinolines. In the presence of a Br?nsted acid [60]fullerene-fused tetrahydroisoquinolines are transformed to [60]fullerene-fused indanes, in which the sulfonamide group can be removed or replaced with an aryl group.     

Asymmetric intramolecular arylcyanation of unactivated olefins via C-CN bond activation

The enantioselective, intramolecular arylcyanation of unactivated olefins via C-CN bond activation has been accomplished using a Ni(0) catalyst and BPh3 co-catalyst. High enantioselectivities are achieved using TangPHOS as a chiral ligand. This method allows the generation of two new C-C bonds and one new quaternary carbon stereogenic center in a single synthetic step, converting readily available benzonitrile substrates into 1,1-disubstituted indanes in 49-85% yield and 92-97% ee.     

Dichotomies in microwave-assisted propargyl-isomerization-Claisen domino sequences dependent on base strengths

Microwave-assisted unimolecular isomerization-Claisen domino reactions of 1,3-di(hetero)aryl propargyl trityl ethers lead, depending on the basicity of the amine, either to the formation of tricyclo[3.2.1.0(2,7)]oct-3-enes (with triethylamine) or to indanes (with DBU). Based upon product analyses and computations, this base dependent dichotomy can be rationalized as a sequel of pericyclic reactions with intermediate protonation and deprotonation.     

Synthesis of various arylated trifluoromethyl substituted indanes and indenes,and study of their biological activity

A series of 1-trifluoromethyl substituted indanes and indenes bearing aryl groups in positions 1 and/or 3 of the indane core have been synthesized mainly by electrophilic cyclization and arylation of the corresponding trifluoromethylated allyl and propargyl alcohols. The distinctly lipophilic compounds thus obtained were tested against various components of human endocannabinoid system. None of the compounds displayed affinity toward CB₁ or CB₂ receptors. Two compounds inhibited monoacylglycerol lipase (MAGL) and three compounds showed inhibition of anandamide (AEA) uptake. The latter can be related to the low-micromolar inhibition of fatty acid amide hydrolase (FAAH) inhibition displayed by one of these compounds.     

Beyond the Corey–Chaykovsky Reaction: Synthesis of Unusual Cyclopropanoids via Desymmetrization and Thereof

Desymmetrization‐based protocols for the synthesis of highly functionalized indeno‐spirocyclopropanes and cyclopropa‐fused indanes have been established through unexpected reactions triggered by the Corey–Chaykovsky reagent. These structures were further elaborated in one step to privileged scaffolds such as fluorenones, indenones, and naphthaphenones. For instance, an acid‐catalyzed transformation of indeno‐spirocyclopropanes provided fluorenones via a homo‐Nazarov‐type cyclization, and naphthaphenones were obtained via an acid‐catalyzed cyclopropane ring‐opening/retro‐Michael sequence.     

Synthetic applications of the nickel-catalyzed cyclization of alkynes combined with addition reactions in a domino process

Carbonickelations of alkynes and functionalization of the resulting vinylnickel moiety have been performed efficiently in a nickel-catalyzed domino cyclization-condensation process. This reaction, which does not require the preparation of any other organometallic reagent, proceeds only by exo-dig cyclization. This convenient and mild method constitutes a one-pot synthesis of substituted dihydrobenzofurans, chromans, isochromans, indoles, or indanes. Theses valuable products are generally obtained in good yields and high stereoselectivity. They are shown to be useful synthons for rapid access to functionalized polycyclic skeletons.     

13C NMR shifts and conformations of substituted indans

¹³C NMR spectra of indan derivatives bearing substituents in the 1, 2, 5 and 6 positions are reported and assigned by LIS measurements and other techniques. Epimeric indanes bearing vicinal oxygen and phenyl or benzyl substituents show ring carbon shielding in the cis relative to the trans isomers, which is compared with corresponding cyclopentane shifts, and indicates the predominance of envelope conformations with pseudoaxial oxygen substituents for the cis isomers. Acetylation shifts show consistently larger shielding at C-β for the trans compounds. Introduction of oxygen at C-5 leads to asymmetric shielding effects at the ortho carbon atoms as soon as there is a substituent in the para position which can participate in mesomeric forms.     

Diazatruxenes from the Condensation Reaction of Indoles with Ninhydrin

The reaction of indoles with ninhydrin has been reported to provide only 1:1 condensation products (cf. A or 8 ) that show good antioxidant and anti‐inflammatory activity. In the present work, our synthetic challenge for the synthesis of innovative, highly substituted tetra‐indole indanes of type 1 via a 4:1 condensation reaction in acetic acid gave two unexpected new products, the diazatruxene derivatives 3 and 4 . The novel structures have been characterized by their analytical and spectral data including 1D‐ and 2D‐NMR. With 5‐chloroindole, only the known 1:1 reaction.