Substituted indanes

Gumylphenol. -Cumylphenol (PGP) or 4-(1-methyl-l-phenylethyl)phenol is produced by the alkylation of phenol with a-methylstyrene under acid catalysis. a-Methylstyrene is a by-product from the production of phenol via the cumene oxidation process. The principal by-products from the production of 4-cumylphenol result from the dimerization and intramolecular alkylation of a-methylstyrene to yield substituted indanes. 4-Cumylphenol [599-64-4] is purified by either fractional distillation or crystallization from a suitable solvent. Purification by crystallization results in the easy separation of the substituted indanes from the product and yields a soHd material which is packaged in plastic or paper bags (20 kg net weight). Purification of 4-cumylphenol by fractional distillation yields a product which is almost totally free of any dicumylphenol. The molten product resulting from purification by distillation can be flaked to yield a soHd form however, the soHd form of 4-cumylphenol sinters severely over time. PGP is best stored and transported as a molten material. 

Osborn, A.G., Scott, D.W. (1978) Vapor-pressure and enthalpy of vaporization of indan and five methyl-substituted indans. J. Chem. Thermdyn. 10, 619-628. 

However, one of the most common mechanisms is undoubtedly proton transfer but whereas in alkene polymerizations this reaction leaves a terminal double bond, in arylene polymerizations these are generally not found. Instead the terminal group is usually a substituted indane formed by an internal Friedel-Crafts alkylation [8, 21, 23], e.g., for a-methyl styrene ... 

It has been shown that, in the presence of lithium diethylamide at —70 °C, bromoben-zoic acids form arynes which may react with arylacetonitriles to yield, predominantly, 2-cyanobenzoic acids. The reaction of alkyl and aryl isocyanides with benzyne may yield benzamide derivatives, showing their ability to act as charge-reversed equivalents to isocyanates. The generation and cyclization of a benzyne-tethered alkyllithium have been reported, and lead to a convenient synthetic route for 4-substituted indans. ... 

Electrophilic nitrations of aliphatic nitriles, carboxylic acids,carboxylic esters, ° and /3-diketones have been reported. The nitration of 2-alkyl-substituted indane-l,3-diones with nitric acid, followed by alkaline hydrolysis, is a standard laboratory route to primary nitroalkanes. ... 

The p -substituted phenylcarbenes p-Me3MC6H4CH (M=Si, Ge, Sn) all give the substituted indane and styrene on pyrolysis, through isomerization to the ortho-substituted carbene (Scheme 3). The indane forms as more than 85% of the products for M = Si and Ge with styrene 5% at 400-500 °C, but only as half of the products of the decomposition for M = Sn, with about 25% styrene. This is formed exclusively at higher temperatures, but probably from the indane decomposing and not the stannirane (Scheme 4) (78TL5193). 

The methodology was useful for the preparation of functionalized benzo-fused carbo-cycles. Isomerically pure 4-substituted indans, 209, could be synthesized by cyclization... 

In a recent study in 80 % aqueous acetonea spirocyclopropyl substituted indan-l-yl p-nitrobenzoate (44) was observed to have unusually high reactivity indicating stabilization both by the cyclopropane and benzene rings. A Hammett pa study of substituent... 

For example, o-bromostyrenes 39 (X = Br), under palladium catalysis, yield substituted indanes 38. Tn this case, careful variation of the conditions is necessary, to prevent the fi-hydride elimination in the intermediate to yield o-dialkenyl arenes 40 (Scheme 3-14) [81]. 

The stereochemistry of acetoxylation at benzyl positions of substituted indanes and ace-naphthenes was investigated in detail [294-296]. the cis—trans ratio of diactoxylated products is significantly larger in the anodic than in chemical processes. 

Kerosene is composed chiefly of hydrocarbons containing 12 or more carbon atoms per molecule. Although the kerosene constituents are predominantly saturated materials, there is evidence for the presence of substituted tetrahydronaphthalenes. Dicycloparaffins also occur in substantial amounts in kerosene. Other hydrocarbons with both aromatic and cycloparaffin rings in the same molecule, such as substituted indane, also occur in kerosene. The predominant structure of the dinuclear aromatics appears to be that in which the aromatic rings are condensed, such as naphthalene, whereas the isolated two-ring compounds, such as biphenyl, are only present in traces, if at all (ASTM D-1840). 

After an early report in the 1960 s on some reactions of alkynylphenyliodonium salts,the chemistry of these species laid dormant until the mid 1980 s. Since then, this field has experienced an intense development. In 1965, Beringer and Galton reported the alkynylation of 2-substituted indane-1,3-dione in good yield, by reaction of the sodium salt of indanedione with phenyl(phenylalkynyl) iodonium chloride (80). 77... 

Pospisil, T., Veetil, A. T., Lovely Angel, P. A., Klan, P, Photochemical Synthesis of Substituted Indan 1 ones Related to Donepezil, Photochem. Photobiol. Sci. 2008, 7, 625 632. 

Table 3.9 Preparation of variously substituted indan-l-ones catalyzed by scandium triflate...

The Studer group presented a new cascade for the highly enantioselec-tive synthesis of substituted indane derivatives. Three stereocenters are formed in the NHC-catalyzed cascade reaction of enals with various p-dike-tones to give the corresponding indane derivatives with excellent stereoselectivity (up to 74% yield, 99% ee). It is predicted that the reaction occurs via a catalytic cycle using oxidative NHC catalysis. Reaction of the enal with NHC in the presence of an oxidant generates an o,p-unsaturated acylazolium ion. Conjugate addition of the likely deprotonated 1,3-dicarbonyl compound... 

PospfSil T, Veetil AT, Antony LAP et al (2008) Photochemical synthesis of substituted indan-1-ones related to Donepezil. Photochem Photobiol Sci 7 625-632... 

Keywords Electron-deficient arenes, unactivated 1,3-dienes, bismuth triflate, nitromethane, room temperature, intramolecular double hydroarylation of 1,3-dienes, regioselectivity, substituted indanes... 

Cacciuttolo, B., Ondet, P., Poulain-Martini, S., Lemiere, G., and Dunach, E. (2014), Bi(OTf)3-catalysed synthesis of substituted indanes by a double hydroaiylation of unactivated 1,3-dienes. Org. Chem. Front., 1, 765-769. 

The important role of solvent in determining the outcome of reactions involving f-BuLi is illustrated by the preparation of 4-substituted indans via cyclization of a benzyne-tethered alkyl-lithium (eq 40). The alkyUithium was generated in a mixture of pentane and diethyl ether at -78 °C using 2 equiv of f-BuLi. ort/io-Lithiation of the substrate was found to be slow under these conditions however, addition of a small amount of THF initiated a cascade involving deprotonation ortho to fluorine by the remaining equivalent of f-BuLi, loss of LiF to generate a... 

A convenient and efficient route to isocoumarins has been described starting from readily available substituted indan-l-ones, which are first converted to the enol form with trifluoroacetic anhydride, then cleaved with ozone. Isocoumarin-4-carboxylic acid is easily prepared from homophthalic acid by addition of Vilsmeier reagent followed by hydrolysis. 

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