Ghasem Aghapour

A rapid and selective iron-mediated reductive Claisen rearrangement of various prop-2’-enyloxyanthraquinones and 2’-chloroprop-2’-enyloxyanthraquinones to 1-hydroxy-2-(prop-2’-enyl)anthraquinones and anthrafurandiones is presented. All reactions are carried out in a mixture of ionic liquids, [Bzmim]Cl (1-benzyl-3-methylimidazolium chloride) and [Hmim]BF4 (1-methylimidazolium tetrafluoroborate), in short reaction times (5–35 min). Our study showed that 1-(prop-2’-enyloxy)anthraquinone is more active than 1-(2’-chloroprop-2’-enyloxy)anthraquinone to perform this rearrangement. © TÜBITAK

An efficient and rapid method is described for the reductive Claisen rearrangement of different propargyloxyanthraquinones to anthra[1,2-b]furan-6,11-diones for first time using iron powder in a mixture of two ionic liquids, namely 1-methylimidazolium tetrafluoroborate [Hmim]BF4 and 1-benzyl-3-methylimidazolium chloride [Bzmim]Cl. The present method is able to execute single or double Claisen rearrangements of 1,4-or 1,5-bispropargyloxyanthraquinones selectively, so that the desired anthra(mono)furandiones or anthra(bis)furandiones are produced, respectively, as the major product. © 2017 Published by NRC Research Press.

An efficient method is described for the mild and rapid tetrahydropyranylation of alcohols and phenols using a catalytic amount of N-chlorosaccharin (1 mol %) and 3, 4-dihydro-2H-pyran under solvent-free condition at room temperature. Benzylic alcohols and phenols containing electron withdrawing or donating groups in various positions of phenyl ring, cinamyl alcohol, primary, secondary, tertiary as well as cyclic alcohols are converted to their corresponding tetrahydropyranyl ethers in short reaction times and in excellent yields via the present method. Primary benzylic alcohols in the presence of secondary ones and also primary or secondary aliphatic alcohols in the presence of tertiary ones can be efficiently tetrahydropyranylated with excellent selectivity via this method. © 2016, Islamic Azad University.

A new and efficient method is described for the oxidative esterification of aromatic aldehydes with different types of alcohols such as primary, secondary, benzylic, allylic and cyclic alcohols and phenols using air as the simplest available oxidant and potassium cyanide in DMF under neutral conditions in high yields. The present method esterifies aldehydes with alcohols in 1:1 molar ratio with excellent chemoselectivity and avoids the use of an external oxidant beside 02 from air.

Direct and oxidative conversion of tetrahydropyranyl and silyl ethers to oximes is described using trichloroisocyanuric acid (TCCA) as a relatively stable and inexpensive oxidant surprisingly in a catalytic amount and hydroxylamine hydrochloride under solvent-free conditions. Oximes can be synthesized from these protected alcohols in the presence of some other functional groups with excellent chemoselectivity using the present tandem catalytic method. Copyright © Taylor & Francis Group, LLC 2015.

A mild and one-pot conversion of benzylic alcohols to their corresponding gem-dichlorides is reported for the first time using chlorodiphenylphosphine (ClPPh2) and 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ) in dichloromethane under neutral conditions and at room temperature. The present method can be efficiently used for preparation of gem-dichlorides even in the presence of some other functional groups with excellent chemoselectivity. Copyright © Taylor & Francis Group, LLC.

Efficient silylation of OH group in alcohols, phenols and oximes is described using a catalytic amount of N-chlorosaccharin and hexamethyldisilazane (HMDS) under mild and solvent-free conditions. This silylation reaction can be carried out with excellent and interesting various selectivities. © 2015 The Chemical Society Located in Taipei & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

(Equation present) A simple, highly selective and efficient method is described for the conversion of primary alcohols, tetrahydropyranyl and silyl ethers to thiocyanates by use of chlorodiphenylphosphine and ammonium thiocyanate. Secondary substrates produce both the two isomeric products, thiocyanate and isothiocyanate, while tertiary ones give isothiocyanates as the only products by this new method. In contrast to previously reported methods based on trivalent phosphorus for this transformation, the present method does not require an electrophile in the presence of trivalent phosphorus (ClPPh 2). The order of activity of these substrates is silyl ether> alcohol > tetrahydropyranyl ether. The present method not only interestingly distinguishes between primary, secondary and tertiary substrates but also converts them to the corresponding thiocyanates with excellent chemoselectivity in the presence of several other functional groups. © 2014 Copyright © Taylor & Francis Group, LLC.

A catalyst-free, high regio- and chemoselective method is described for the mild conversion of wide varieties of epoxides directly to their corresponding vicinal haloesters using quaternary ammonium halides R4N +X- (X equals; Cl, Br, I; R = n-butyl, n-pentyl, n-hexyl) in the presence of an aliphatic or aromatic carboxylic anhydride at room temperature under neutral and solvent-free conditions. © 2013 Copyright Taylor and Francis Group, LLC.

In spite of many reports in the literature concerning with oxidation of benzylic alcohols to carbonyl compounds with 2,3-dichloro-5,6- dicyanobenzoquinone (DDQ) in stoichiometric amounts or even more, we surprisingly found that benzylic alcohols are directly oxidized to oximes using a catalytic amount of DDQ in the presence of hydroxylamine hydrochloride under solvent-free conditions. The present tandem catalytic method can be efficiently used for preparation of oximes in the presence of some other functional groups with excellent chemoselectivity.

A new method is described for the efficient and high regioselective conversion of epoxides to symmetrical and unsymmetrical vic-dihalides in high yields using chlorodiphenylphosphine and N-halosuccinimides under solvent-free and neutral conditions and at room temperature. Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file. Copyright © Taylor & Francis Group, LLC.

A catalyst-free, direct, high regio-, and chemo-selective method is reported for the facile conversion of a wide variety of epoxides to their corresponding 2-thiocyanatoalkyl alkanoates, which contain two important functional groups (ester and thiocyanate), using a mixture of tetrabutylammonium rhodanide ((n-Bu)4NSCN) and an aliphatic or aromatic carboxylic anhydride under neutral and solvent-free conditions.

Epoxides are efficiently and easily converted to their corresponding -hydroxy thiocyanates by NH4SCN in refluxing acetonitrile in a regio- and chemoselective manner under neutral conditions without using a catalyst, in spite of the use of many different catalysts reported in the literature for this purpose. Copyright © Taylor & Francis Group, LLC.

A new method is described for the mild and high regioselective conversion of epoxides to β-chlcrohydrins in high yields even in the presence of alcohols, carboxylic acids, oximes, amides, thiols and tetrahydropyranyl ethers using chlorodiphenylphosphine (ClPPh2) under solvent-free and neutral conditions at room temperature and in short reaction times. In addition, some other functional groups such as carbon-carbon double bonds, ester groups and also phenyl ring that are present in the epoxide molecules remain intact in this method.

Aldehydes and ketones are easily converted to their corresponding gem-dichlorides using a mixture of chlorodiphenylphosphine and N-chlorosuccinimide (ClPPh2/NCS) in dichloromethane under neutral conditions and at room temperature. Copyright © Taylor & Francis Group, LLC.

Aldoximes are immediately converted to their corresponding nitriles with a mixture of triphenylphosphine and 2,3dichloro-5,6-dicyanobenzoquinone in dichloromethane under neutral conditions at room temperature., Nitriles are also formed from the reaction of primary amides with this reagent in refluxing acetonitrile under neutral conditions.