Arylation of halogenated pyrimidines via a Suzuki coupling reaction

The Suzuki coupling reaction has been used extensively for the synthesis of a wide variety of unsymmetrical biaryl compounds. We have extended this reaction to demonstrate the utility of preparing monophenyl-, diphenyl-, or triphenylpyrimidine depending on the reaction conditions. Further, it has been shown that chloropyrimidine substrates are preferable over iodo-, bromo-, or fluoropyrimidines.     

Palladium-catalyzed reaction of bromine- and iodine-containing isothiazoles with olefins

3-Bromo-4-alkenylisothiazoles were synthesized by the reaction of 3-bromo-4-iodoisothiazole with olefins in the presence of palladium acetate Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 534–536, March, 1998.     

A concise synthesis of chilenine via a sequential reaction process

A new short synthesis of chilenine has been achieved in two steps. The precursor amide was readily prepared by the condensation of the corresponding amine and acid. Treatment of the amide with oxalyl chloride in the presence of AlCl₃ at room temperature afforded the desired product chilenine through sequential Friedel-Crafts acylation, amide cyclization to imide, and intramolecular Friedel-Crafts type reaction. The synthesis suggests a new potential of oxalyl chloride for a two-carbon synthon.     

Construction of a six-membered fused N-heterocyclic ring via a new 3-component reaction: synthesis of (pyrazolo)pyrimidines/pyridines

A conceptually new three-component reaction was developed to construct a six-membered fused N-heterocyclic ring affording (pyrazolo)pyrimidines/pyridines as potential inhibitors of PDE4. The reaction is catalyzed by triflic acid in acetic acid in the presence of aerial oxygen.     

A quantitative synthesis of β-carboxylated thiolophosphates via a Michael reaction

Reactions of O,O′-dialkylthiophosphoric acids with acrylates provide a direct synthetic route to β-carboxylated thiolophosphates. This Michael addition, without solvent, is quantitative at 90°C in 1 h for the 2/1 thiophosphoric acid/acrylate ratio. Moreover, this excess of thiophosphoric acid can be reused for further reactions.     

A novel microwave-mediated one-pot synthesis of indolizines via a three-component reaction

[reaction: see text] The microwave-mediated three-component reaction of acyl bromide, pyridine, and acetylene is catalyzed by basic alumina to give corresponding indolizines in excellent yields in a one-pot reaction.     

A convenient synthesis of olefins via deacylation reaction

A convenient and environmentally-friendly synthetic method of olefins via deacylation reaction is described. The reaction gives olefins by condensation of aldehydes with a variety of 1,3-dicarbonyl compounds in the presence of anhydrous potassium carbonate at room temperature in high yields (70-90%) in one step. The synthetic potential of this strategy can be used as an alternative procedure to the Wittig, Wittig-Horner reactions. The stereochemistry of the resulted olefins was determined by NOE experiment with correct radio frequency and X-ray analysis. The E/Z selectivity of the deacylation reaction depends on the α-substituents of the 1,3-dicarbonyl compounds.     

A new synthesis of flavonoids via Heck reaction

Several naturally occurring flavonoids have been synthesised following a new proposed method based on the use of the Heck reaction. The key step involves the coupling of an aryl vinyl ketone with an aryl iodide. This procedure affords the flavonoid moiety in a single step.     

Asymmetric synthesis of naproxen via a pinacol-type reaction

An asymmetric pinacol-type rearrangement was used in the synthesis of (S)-naproxen. The pinacol-type reaction of a vicinal diol provided an -aryl ketone which was oxidized with sodium hypochlorite in the presence of methanol to the methyl ester of naproxen.     

A synthesis of spirofuran-indenoquinoxalines via isocyanid-based one-pot four-component reaction

A simple and versatile procedure for the combinatorial synthesis of (Z)-dialkyl-5-(alkylimino)-5Hspiro[ furan-2,11'-indeno[1,2-b]quinoxaline]-3,4-dicarboxylates via the catalyst-free one-pot fourcomponent reaction of ninhydrin, benzene-1,2-diamines, dialkyl acetylenedicarboxylates and isocyanides is described.     

The vilsmeier-haack reaction. IV. Reaction of phosphorus oxychloridedimethylformamide with semicarbazones

Ketone semicarbazones react with two moles of phosphorus oxychloride-dimethylformamide with the formation of 3-substituted pyrazole-4-carboxaldehydes. Aldehyde semicarbazones give, with one mole of phosphorus oxychloride-dimethylformamide, amidazines.     

A new and high yielding synthesis of unstable pyrroles via a modified Clauson-Kaas reaction

An investigation of the reaction requirements to effect the Clauson-Kaas pyrrole synthesis led to the formulation of a new procedure that avoids the contact of pyrroles to heat or strongly acidic conditions that cause decomposition of the desired products. The procedure involves mild hydrolysis of 2,5-dimethoxytetrahydrofuran in water to the activated species 2,5-dihydroxytetrahydrofuran that reacts with primary amines in an acetate buffer at room temperature to give N-substituted pyrroles in high yield. In the case of chiral amines, pyrrole formation proceeds with no detectable epimerisation. Acid- or heat-sensitive pyrroles are also obtained in high yield and purity.     

A rapid and efficient synthesis of a new pyrrolobenzodiazocines via an intramolecular Friedel-Crafts reaction

New pyrrolobenzodiazocines 3 have been prepared by an intramolecular Friedel-Crafts process from pyrrolobenzoacrylamides 2. The cyclisation process involving a 1,4-intramolecular addition of a pyrrole onto acrylamide led to the formation of an eight-membered ring.     

Stereospecific synthesis of dienones via a torquoselective retro-Nazarov reaction

[reaction: see text] Enol ethers are cleaved via a three-step sequence involving cycloaddition with dichloroketene, ring expansion with diazomethane, and a base-mediated retro-Nazarov reaction. The latter conrotatory process proceeds torquoselectively and stereospecifically in accord with theoretical predictions.     

N-Heterocyclic carbene-catalyzed synthesis of acetyltributylcitrate via a transesterification reaction

A new methodology for the synthesis of a green plasticizer acetyltributylcitrate through a transesterification reaction was developed. Under the catalysis of alkyl-substituted imidazol-type N-heterocyclic carbenes, tributyl citrate can react with vinyl acetate smoothly to give ATBC in high yield.     

Microwave-assisted novel and efficient one-pot synthesis of fused steroidal and non-steroidal isothiazoles

An efficient microwave promoted one-pot synthesis of steroidal and non-steroidal isothiazole derivatives from corresponding β-bromo-α,β-unsaturated aldehydes has been described using a sodium thiocyanate-urea system. The β-bromo-α,β-unsaturated aldehydes derivatives are efficiently synthesized from corresponding cyclic ketones using Vilsmeir formylation reaction. The synthetic protocol is also applied for the synthesis of antifungal brassilexin.     

A novel diastereoselective synthesis of (Z)-fluoroalkenes via a Nozaki-Hiyama-Kishi-type reaction

A highly diastereoselective and straightforward synthesis for (Z)-2-fluoroallylic alcohols via a Nozaki-Hiyama-Kishi-type reaction with the corresponding bromofluoroolefins was developed, providing an easy access to highly interesting fluorinated synthons.     

A stereoselective formal total synthesis of (+)-hyperaspine via a tandem aza-Michael reaction

A stereoselective formal total synthesis of (+)-hyperaspine via a tandem aza-Michael reaction as the key step in good yield is reported.     

An expedient synthesis of murrayaquinone A via a novel oxidative free radical reaction

Murrayaquinones A–D is a group of four bioactive carbazole-1,4-dione natural products isolated from the root bark of the plant Murraya eucrestifolia hayata. Murrayaquinone is synthesized in five steps starting from the commercially available 2,4,5-trimethoxybenzaldehyde with an overall yield of 45%. The novelty of this murrayaquinone synthesis is in the use of a Mn(OAc)₃ mediated oxidative radical reaction of a N-benzylaminoquinone derivative with 2-cyclohexen-1-one for the late-stage indole ring construction.