A facile route to 5-alkyl-2(3H)-furanones by photoisomerisation of enedicarbonyl compounds

A new and useful synthesis of a title compounds is reported. They can be obtained easily by photocyclization of enedicarbonyl compounds 3 and 4. A different behaviour, ascribed to the geometry of a double bond, is observed; 3 are converted only to butenolides 5, while trans-isomers 4 are converted into alkyl-furyl-ketones 5 and 6. A possible mechanism is described.     

Palladium-catalyzed cross-coupling reactions of 2-diazonaphthoquinones with arylboronic acids

Palladium-catalyzed cross-coupling reactions of 2-diazonaphthoquinones and arylboronic acids proceeded by the treatment with Pd(OAc)₂ in acetic acid to afford 2-aryl-1-naphthols.     

A facile solid-phase synthesis of substituted 2(5H)-furanones from polymer-supported alpha-selenocarboxylic acids

The synthesis of polystyrene-supported alpha-selenoacetic acid, alpha-selenopropionic acid, and alpha-selenophenylacetic acid is described. The reaction of the dilithio derivatives of polymer-supported alpha-selenocarboxylic acids with racemic epoxides or optically active styrene oxide afforded polystyrene-supported gamma-substituted alpha-selenobutyrolactones. The alpha-alkylation reaction of gamma-substituted polystyrene-supported alpha-selenobutyrolactones provided another route for the synthesis of polystyrene-supported alpha,gamma-disubstituted alpha-selenobutyrolactones. Subsequent oxidation-elimination with an excess of 30% hydrogen peroxide at room temperature afforded substituted (3- and 5-mono-; 3,4- and 3,5-di) 2(5H)-furanones in high yields and good purities.     

An Efficient Synthesis of Highly Optically Active 4-Substituted-2（5H）-furanones from Chiral 3-Bromo-2（5H）-furanone

Highly optically active 4-substituted-2(5H)-furanones 6a-6j were obtained in good yields with de≥98% by the tandem Michael addition/elimination reaction of chiral 3-bromo-2(SH)-furanone (4a), which was conveniently prepared starting from 2-furaldehyde under mild conditions. The products were identified on the basis of their satisfactory elemental analysis and spectroscopic data of IR, UV, ^1H NMR, ^13C NMR and mass spectra. The stereochemistry and absolute configuration of this type of compounds were established by the X-ray crystallographic study. The reaction provided a short and efficient synthesis of the interesting highly optically active 4-subsdtuted-2(5H)-furanones containing an active pyrimidine and a purine base group.     

Asymmetric Diels-Alder reactions with 5-menthyloxy-2-(5H)-furanone

A new class of chiral dienophiles, 5-alkoxy-2(5H)-furanones, has been developed. Both enantiomers of 5-menthyloxy-2(5H)-ftiranone are readily available in enantiomerically pure form, starting from furfural and d- or l-menthol. Excellent diastereoselectivities (d.e. β99%) are obtained in thermal Diels-Alder reactions with several cyclic and acyclic dienes. The use of silyl dienol ethers has resulted in new routes to enantiomerically pure cyclohexanones in a highly regioselective manner.     

An efficient route to 4-substituted coumarins, 2(5H)-furanones, and pyrones via palladium-catalyzed couplings of alkenyl tosylates with organoindium reagents

Highly efficient palladium-catalyzed couplings of alkenyl tosylates with organoindium reagents under mild conditions are described, which give rise to 4-substituted coumarins, 2(5H)-furanones, and pyrones in good to excellent yields.     

Syntheses of 4-(1-alkynyl)-2(5H)-furanones and coumarins via the palladium catalyzed cross-coupling reactions of potassium alkynyltrifluoroborates

An efficient synthesis of 4-(1-alkynyl)-2(5H)-furanones has been developed utilizing a palladium catalyzed coupling reaction of β-tetronic acid bromide with potassium alkynyltrifluoroborates in the absence of base. 4-Alkynylcoumarins were also synthesized using this method. The reactions are straightforward and the yields are excellent.     

Palladium-catalyzed cross-coupling reactions of (2-pyridyl)allyldimethylsilanes with aryl iodides

[reaction: see text] (2-Pyridyl)allyldimethylsilanes were found to be novel pyridyl transfer reagents in palladium-catalyzed cross-coupling reactions of various aryl iodides in the presence of silver(I) oxide as an activator.     

CuO nanoparticles: an efficient and recyclable catalyst for cross-coupling reactions of organic diselenides with aryl boronic acids

We present here an efficient and ligand-free cross-coupling reaction of organic diselenides with aryl boronic acids using a catalytic amount of CuO nanoparticles in DMSO at 100 °C under air atmosphere. This is a general cross-coupling reaction and was performed with organic diselenides and aryl boronic acids bearing electron-withdrawing and electron-donating groups affording the corresponding selenides in good to excellent yields. The CuO nanoparticles can be easily recovered and utilized for further catalytic reactions.     

Palladium-catalyzed cross-coupling reactions of 2-iodo-4-(phenylchalcogenyl)-1-butenes

[reaction: see text] 2-Iodo-4-(phenylchalcogenyl)-1-butenes 2 or 3, which are derived from the ring-opening reaction of methylenecyclopropanes (MCPs) 1 by iodine, can be applied to some palladium-catalyzed cross-coupling reactions such as the Sonogashira, Heck, Kumada, Suzuki, and Negishi reactions under mild conditions to give the corresponding coupling products in good yields. These reactions proceeded smoothly at room temperature (20 degrees C) in most cases without any phosphine ligand and additive. The phenylchalcogenyl group plays an important role in the reactions and a plausible reaction mechanism has been proposed.     

Addition reactions of thiazol-5(4H)-ones—II : Cycloaddition and Michael addition reactions of 4-substituted 2-phenylthiazol-5(4H)-ones

The mixture of adducts formed under mild conditions between a 4-substituted 2-phenylthiazol-5(4H)-one and an electron-deficient alkene is shown to include a stable cycloadduct and a Michael adduct formed through the 2- or the 4-position of the thiazolone. The reaction can be diverted towards the Michael adduct entirely, by adding traces of aqueous alkali to the reactants in acetone solution. A novel type of 1:2-adduct is present in the reaction mixture, and is shown to be formed through reaction of the cycloadduct with the alkene. A product formed by extrusion of carbonyl sulphide from the cycloadduct is the same as that obtained from the analogous oxazolone and the alkene, but generally the differences between the propensity of oxazolones and thiazolones to undergo various types of addition reaction with representative dipolarophiles are shown to be substantial.     

PdCl2-catalyzed two-component cross-coupling cyclization of 2,3-allenoic acids with 2,3-allenols. An efficient synthesis of 4-(1',3'-dien-2'-yl)-2(5H)-furanone derivatives

Cross-coupling cyclization reaction between 2,3-allenoic acids 1 and 2,3-allenols 2, in which two allenes functioned differently, was realized to afford 4-(1',3'-dien-2'-yl)-2(5H)-furanone derivatives 3. The reaction may proceed via an oxypalladation, insertion, and beta-hydroxide elimination process. A high E-stereoselectivity of the new formed C=C double bond was observed.     

Rhodium-catalyzed carbonylative arylation of alkynes with arylboronic acids: an efficient and straightforward method in the synthesis of 5-aryl-2(5H)-furanones

5-Aryl-2(5H)-furanones can be synthesized by the Rh-catalyzed reactions of arylboronic acids with internal alkynes under a CO atmosphere.     

Palladium-catalyzed reactions of N-allylbenzotriazoles with amines and sulfonamides: A facile route to functionalized allylamines and N-allylsulfonamides

A variety of functionalized N-allylamines and N-allylsulfonamides are synthesized by Pd(II)-catalyzed intermolecular amination of the corresponding N-allylbenzotriazoles.     

Palladium-catalyzed domino ring-opening/carboxamidation reactions of N-tosyl aziridines and 2-iodothiophenols: a facile and efficient approach to 1,4-benzothiazepin-5-ones

A novel and efficient domino procedure has been developed for the synthesis of 1,4-benzothiazepin-5-ones from simple and readily accessible N-tosyl aziridines and o-iodothiophenols. This process involves aziridines ring-opening with o-iodothiophenols, followed by palladium-catalyzed intramolecular carboxamidation. The scope and limitation of this transformation have been investigated in detail by using various aziridines and o-iodothiophenols.     

New synthetic methods for 4-amino-2(5H)-furanones

Two new efficient methods are disclosed for the synthesis of the title compounds: (1) base-promoted ring closure of 2-acyloxy alkanenitrile and (2) acid-mediated lactonization of t-butyl 4-alkoxy-3-amino-2-alkenoates.