Polymer-supported Mukaiyama reagent: a useful coupling reagent for the synthesis of esters and amides

Polymer-supported N-alkyl-2-chloro pyridinium triflate was synthesized in one step from Wang resin. This reagent proved to be a very effective coupling reagent for the synthesis of esters or amides from carboxylic acids and alcohols or amines (primary and secondary). [reaction: see text]     

Tetrahydrochromenylium and -Thiochromenylium Salts from Triketones of the 2-(3-Oxopropyl)cyclohexane-1,3-dione Series

We have worked out the optimal conditions for synthesis of 2,4-diaryl-5-oxo-5,6,7,8-tetrahydrochromenylium and -thiochromenylium salts based on triketones of the 2-(1,3-diaryl-3-oxopropyl)cyclohexane-1,3-dione series. For the first time, along with 5-oxo-substituted salts, we have obtained 5-thioxo-5,6,7,8-tetrahydrothiochromenylium salts. A necessary condition for the formation of the latter on treatment with acids and S-nucleophiles is the presence of electron-donor groups on the aryl substituents of the indicated triketones.     

Characteristics of heterocyclization of triketones of the 2-(3-oxopropyl)cyclohexane-1,3-dione series with hydroxylamine hydrochloride

A rearrangement that leads to the formation of mixtures of 2,4- and 2,3-diaryl-substituted 5-oxotetrahydroquinoline oximes was observed in the heterocyclization of oxo 1,5-diketones of the 2-(3-oxopropyl)cyclohexane-1,3-dione series, as well as in the recyclization of 5-oxotetrahydro-4H-chromenes, in the presence of excess hydroxylamine hydrochloride. It was established that the rearrangement proceeds only when electron-donor groups are present in the starting compounds.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 209–214, February, 1990.     

Sequence of alkylation of cyclohexane-1, 3-dione. Alternative synthesis of (±)-Angustione

A method is proposed for introducing one, two, or three alkyl substituents into positions 4 and 6 of the cyclohexane-1, 3-dione molecule by successive alkylation under the action of strong bases. (±)-Angustione (a natural β-diketone) has been synthesized. Institute of Bioorganic Chemistry, Academy of Sciences of the Belorussian SSR, Minsk. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 460–463, July–August, 1991.     

Gadolinium(III) chloride: a novel and an efficient reagent for the synthesis of homoallylic alcohols

Carbonyl compounds efficiently undergo nucleophilic addition reactions with allylstannanes in the presence of GdCl₃·6H₂O in acetonitrile under extremely mild reaction conditions to give the corresponding homoallylic alcohols in excellent yields and with high chemoselectivity.     

Cyclopentane-1,3-dione bis(4-methylthiosemicarbazone) monohydrochloride as a spectrophotometric reagent for the determination of chlorate in perchloric acid medium

1,3-Cyclopentanedione bis(4-methylthiosemicarbazone) monohydrochloride produces colored solutions with chlorate ions in strongly acid medium. The yellow color obtained has been used to propose a spectrophotometric method of C10₃^? determination in the concentration range 0.5–6.0 ppm (molar absorptivity 1.26 × 10⁴ liters mol^?1 cm^?1 at a wavelength of 397 nm).     

3,3,3-trichloropropyl-1-triphenylphosphorane: a reagent for the synthesis of (Z)-1,3-enynes, (Z,Z)-1-chloro-1,3-dienes, and 1,3-diynes

3,3,3-Trichloropropyl-1-triphenylphosphonium chloride is conveniently prepared from 2-chloroethanol, triphenylphosphine, and trichloroacetic acid. Deprotonation of this reagent generates 3,3,3-trichloropropyl-1-triphenylphosphorane, which reacts with aldehydes to give trichloromethylated (Z)-olefins, which are useful for the synthesis of (Z)-1,3-enynes, (Z,Z)-1-chloro-1,3-dienes, and 1,3-diynes in high yields and stereospecificities.     

Reactions of 2-hydroxynaphthazarins with cyclohexane-1,2-dione as a new method for the synthesis of pyranonaphthazarin systems

Russian Chemical Bulletin -     

Cascade synthesis with (triphenylphosphoranylidene)-ethenone as a versatile reagent for fast synthesis of heterocycles and unsaturated amides under microwave dielectric heating

A general procedure for the synthesis of a large variety of compounds comprising an alpha, beta,-unsaturated carbonyl functionality was developed. The use of one-pot cascade synthesis with (triphenylphosphora-nylidene)ethenone as a versatile reagent for various formations including heterocycles of different ring sizes and unsaturated amides in combination with microwave dielectric heating is described. The method was used to synthesize a small library of unsaturated amides.     

Design and synthesis of novel spirocyclopropyl cyclohexane-1,3-diones and -1,3,5-triones for their incorporation into potent HPPD inhibitors

We report the design and the efficient synthesis of novel spirocyclopropyl cyclohexane-1,3-dione and -1,3,5-trione units to be incorporated into potent HPPD inhibitors. New routes involving original combinations of synthetic equivalents of α-cyclopropyl ketone-α-anion and α-cyclopropyl ester-β-cation are described.     

Synthesis of 5-(trifluoromethyl)cyclohexane-1,3-dione and 3-amino-5-(trifluoromethyl)cyclohex-2-en-1-one: new trifluoromethyl building block

A simple synthesis of 5-(trifluoromethyl)cyclohexane-1,3-dione and 3-amino-5-(trifluoromethyl)cyclohex-2-en-1-one from the sodium salt of methyl or ethyl-4-hydroxy-2-oxo-6-(trifluoromethyl)cyclohex-3-en-1-oate is demonstrated. The compounds represent highly functionalized reactive intermediates for the synthesis of organic and heterocyclic compounds containing a trifluoromethyl group.     

Triphenylmethyldifluoramine: a stable reagent for the synthesis of gem-bis(difluoramines)

The conversion of ketones into geminal bis(difluoramines) can be achieved under mild two-phase reaction conditions by employing triphenylmethyldifluoramine as an in situ source of difluoramine.     

3-Bromocyclohexane-1,2-dione as a useful reagent for Hantzsch synthesis of thiazoles and the synthesis of related heterocycles

We describe the use of 3-bromocyclohexane-1,2-dione, an air stable, versatile reagent for the Hantzsch thiazole synthesis and the synthesis of other closely related heterocycles.     

Solid-state structures of 2-(4-hydroxyphenyl)-substituted phenalene-1,3-dione and indan-1,3-dione

The structure of 2-(4-hydroxyphenyl)-substituted indan-1,3-dione and phenalene-1,3-dione is investigated using a combination of solid-state NMR, single crystal X-ray analyses and quantum chemical calculations. It is shown that 2-(4-hydroxyphenyl)-1,3-indandione exists as a diketo tautomer while 2-(4-hydroxyphenyl)-1,3-phenalenedione exists in the enol form.     

A novel reagent (N_succinimidyl diphenylphosphate) for synthesis of active ester and peptide

N-succinimidyl diphenylphosphate (SDPP) was prepared. This reagent was useful for the preparation of active esters and peptides in stead of dicyclohexylcarbodiimide.     

Gamma-allyl phosphinoyl phenyl sulfone (GAPPS): a conjunctive reagent for the synthesis of EE, EZ, and ET 1,3-dienes

A three-operation conjunctive strategy is available for the synthesis of EE, EZ, and ET dienes. This protocol employs a sequential Wadsworth-Emmons reaction using a GAPPS reagent followed by alkylation of an allylic sulfone anion, and finally ligand-mediated, palladium-catalyzed desulfonylation.