An efficient synthesis of 3-substituted 3H-pyrimidin-4-ones

[reaction: see text] A novel and practical synthesis of 3-substituted 3H-pyrimidin-4-ones is described. The key step involves the cyclization of enamide esters, derived from readily available beta-keto esters, with trimethylaluminum and various primary amines.     

A new multicomponent approach to highly functionalized 2,3-dihydroisoxazoles

The synthesis of highly functionalized 2,3-dihydroisoxazoles by a one-pot multicomponent reaction of an aldehyde, hydroxamic acid, and malononitrile or methyl cyanoacetate is described.     

Parallel synthesis of 3-amino-4H-quinolizin-4-ones, fused 3-amino-4H-pyrimidin-4-ones, and fused 3-amino-2H-pyran-2-ones

On the basis of the enaminone methodology, libraries of 3-amino-4H-quinolizin-4-ones, fused 3-amino-4H-pyrimidin-4-ones, and fused 3-amino-2H-pyran-2-ones were synthesized by the solid-phase and by the solution-phase parallel synthesis. The solution-phase approach turned out to be advantageous over the solid-phase approach. The solution-phase synthesis afforded, in most cases, analytically pure products in high yields, whereas the solid-phase approach gave products in poor yields and in low purity.     

A new route to highly functionalized heterocyclic rings

A novel cascade reaction has been developed for the rapid construction of heterocyclic rings. The cyclization is thermally induced and does not involve the use of metal ions. This highly efficient construction of furans has been developed during studies directed toward the synthesis of the antibiotic lactonamycin 1.     

A new approach to the facile synthesis of 2-substituted-quinazolin-4(3H)-ones

A new approach to the facile synthesis of 2-substituted-quinazolin-4(3H)-ones and its derivatives using the condensation reaction of substituted 2-aminobenzamide and orthoesters is reported.     

Carbohydrate derived bicyclic azetidin-3-ones as scaffolds for highly functionalized azetidines

Bicyclic azetidin-3-ones with no acidic α-hydrogens, prepared in good yields via cis-2,4-di-O-triflates of pyranosides, are stable divergent intermediates for the synthesis of highly substituted azetidines, as illustrated by the synthesis of (2R,3R,4R)-3-hydroxy-4-(hydroxymethyl)-3-methylazetidine-2-carboxylic acids. Preliminary studies on the reactions of bicyclic azetidinones indicate their potential as scaffolds for novel complex azetidines.     

Efficient synthesis and fluorescence properties of highly functionalized 2-aryl-quinazolin-4(3H)-ones

Three different methodologies for the preparation of highly substituted 2-aryl-quinazolin-4(3H)-ones including short and high-yielding reaction sequences are described. The 2-aryl-substituent of most of the target compounds bears three functional groups. The fluorescence properties of these compounds are presented and potential correlations between structure and optical properties are discussed.     

A divergent approach to highly substituted benzothiepinones and to 2,3-dihydrothieno[2,3-b]thiopyran-4-ones

The radical addition-transfer of S-(2-fluoro-phenacyl)xanthates can be used to construct rapidly benzothiepinones, including libraries of complex aza-bridged derivatives, and highly functionalized 2,3-dihydrothieno[2,3-b]thiopyran-4-ones.     

N-Isocyaniminotriphenylphosphorane (Ph3PNNC) as a metal-free catalyst for the synthesis of functionalized isoindoline-1-ones

A novel application in the field of N-isocyaniminotriphenylphosphorane (Ph₃PNNC) chemistry has been introduced in this work. A series of substituted isoindolin-1-one ring systems has been successfully synthesized through a novel and efficient multicomponent reaction of methyl 2-formylbenzoate and primary amines in the presence of N-isocyaniminotriphenylphosphorane (Ph₃PNNC) as a catalyst. This one-pot three component reaction (3-CR) gives high yield using N-isocyaniminotriphenylphosphorane (Ph₃PNNC) as a metal-free catalyst under mild conditions.     

A diversity oriented four-component approach to tetrahydro-beta-carbolines initiated by Sonogashira coupling

A consecutive four-component synthesis of highly-substituted tetrahydro-beta-carbolines can be achieved by a coupling-aminatio-aza-annulation-Pictet-Spengler (CAAPS) sequence creating five new sigma-bonds and four new stereocenters in a one-pot fashion. The structures were unambiguously supported by X-ray structure analyses.     

A simple,diversity oriented synthesis of highly substituted pyridines

A particularly straightforward and efficient protocol for the synthesis of highly substituted pyridines, based on a condensation reaction of β‐aminocrotonitrile and easily accessible (E)‐2‐oxo‐4‐aryl‐but‐3‐enoic acids and (E)‐4‐oxo‐4‐aryl‐but‐2‐enoic acids is described. J. Heterocyclic Chem., (2011).     

A simple and efficient approach to the synthesis of highly functionalized fused benzochromenes

Protonation of the reactive intermediates produced in the reaction between tert-butyl isocyanide and dimethyl acetylenedicarboxylate or dibenzoylacetylene, by 1-naphthol, 2-naphthol, 2,3-dihydroxynaphthalene, 2,7-dihydroxynaphthalene or 4-methyl-8-hydroxycoumarin leads to vinylnitrilium cations, which undergo carbon-centered Michael type addition with the conjugate base of the naphthols to produce highly functionalized benzochromenes.     

A simple approach to pyrazol-3-ones via diazenes

An efficient entry into pyrazol-3-ones is described starting from propenoic acids that were first transformed into the corresponding hydrazides. Oxidation of the hydrazides gave the diazenes and the latter cyclized to pyrazol-3-ones on treatment with ZrCl₄. The methoxycarbonyl protection of the N-1 of the pyrazolone derivatives was easily removed under mild reaction conditions.     

Photooxygenation of 5-dialkylamino-4-pyrrolin-3-ones. Synthesis of highly functionalized ureas, 2-oxazolidinones, and 2-oxazolinones

5-Dialkylamino-4-pyrrolin-3-ones, available from cyclocondensation of amidines with dimethyl acetylenedicarboxylate (DMAD), undergo rapid singlet oxygenation to give highly functionalized ureas by way of a 1,2-dioxetane cleavage of the initially formed [2 + 2] cycloadducts. These latter compounds undergo cyclization to 2-oxazolidinones in MeOH. Catalytic hydrogenation of the ureas in EtOAc gives 2-oxazolinones. The DBU-DMAD adduct undergoes photooxygenation by an entirely different pathway to give a large ring heterocycle.     

A new approach to CF3-containing 3,4-dihydroquinazolin-2(1H)-ones

Russian Chemical Bulletin - A new approach to CF3-containing 3,4-dihydroquinazolin-2(1H)-ones based on the condensation of 5-acetyl-6-methyl-1-phenyl-4-trifluoromethylpyrimidin-2(1H)-one with...     

Thermolysis and acid-catalyzed decomposition of 4-diazotetrahydrofuran-3-ones. A new efficient synthesis of tetrasubstituted dihydrofuran-3-ones

Russian Journal of Organic Chemistry -     

Nanoporous graphitic-C3N4@carbon metal-free electrocatalysts for highly efficient oxygen reduction

Based on theoretical prediction, a g-C(3)N(4)@carbon metal-free oxygen reduction reaction (ORR) electrocatalyst was designed and synthesized by uniform incorporation of g-C(3)N(4) into a mesoporous carbon to enhance the electron transfer efficiency of g-C(3)N(4). The resulting g-C(3)N(4)@carbon composite exhibited competitive catalytic activity (11.3 mA cm(-2) kinetic-limiting current density at -0.6 V) and superior methanol tolerance compared to a commercial Pt/C catalyst. Furthermore, it demonstrated significantly higher catalytic efficiency (nearly 100% of four-electron ORR process selectivity) than a Pt/C catalyst. The proposed synthesis route is facile and low-cost, providing a feasible method for the development of highly efficient electrocatalysts.     

A highly efficient route to C-3 alkyl-substituted indoles via a metal-free transfer hydrogenation

A highly efficient route to C-3 alkyl-substituted indoles via completely metal-free catalytic transfer hydrogenation of 3-indolemethanols was developed. This process proceeds via vinylogous iminium intermediates formed in situ in the presence of Brønsted acids, and Hantzsch ester is used as the reductant. The reduction works extremely well with a large substrate scope, and the yields exceed 90% in almost all cases.     

A new approach to functionalized spiropiperidines through tandem RCM and nitrogen-directed reactions

The synthesis of a functionalized spiropiperidine via a tandem ring closing metathesis strategy is described, furthermore, the regio- and stereoselective functionalization of this compound has been achieved through a novel nitrogen-directed epoxidation reaction.     

A facile route to highly functionalized ketenimines

Summary A one-pot synthesis of highly functionalized ketenimines by reaction of alkyl isocyanides with dialkyl acetylenedicarboxylates in presence of 1,3-diphenylpropan-1,3-dione is reported.

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Ein einfacher Weg zu hochfunktionalisierten Keteniminen

Zusammenfassung Es wird eine Eintopfsynthese hochfunktionalisierter Ketenimine durch Reaktion von Isocyaniden mit Dialkylacetylendicarboxylaten in Gegenwart von 1,3-Diphenylpropan-1,2-dion beschrieben.