Synthesis of fused tricyclic gamma-lactones mediated by manganese(III) acetate

Exposure of cyclic alkenes bearing a carboxylic acid and a malonate group to manganese(III) acetate and an appropriate copper(II) salt provides the corresponding tricyclic gamma-lactones in good yield.     

Synthesis of 2(3H)-furanones via electrophilic cyclization

A variety of highly substituted 2(3H)-furanones are readily prepared from 3-alkynoate esters and the corresponding acids via electrophilic cyclization. Successful electrophiles in this process include I2, ICl, and PhSeCl. This highly efficient process proceeds under mild conditions, tolerates various functional groups, and generally provides substituted 2(3H)-furanones in good to excellent yields.     

Reactions of 2(3H)-furanones

This review article presents a systematic overview of approaches and reactivity data for 2(3H)-furanones, published from 1999 until 2018.     

A new and facile synthesis of 3(2H)-furanones via carboxylation- decarboxylation sequence

One-pot synthesis of 3(2H)-furanones from α-ethynyl tertiary alcohols and acyl halides has been achieved in the presence of a palladium complex under CO₂ pressure.     

A new convinient synthesis of 3(2H)-furanones

A selective oxidative fission of the heterocyclic nucleus of 5-methyl-2-(acylmethyl)furans or 2-(5-methyl-2-furyl)-1,3-dicarbonyl compounds by m-chloroperbenzoic acid allows the easy synthesis of the 3(2H)-furanone system.     

A convenient synthesis of 2,2-disubstituted 3(2H)-furanones

2,2-Disubstituted 3(2H)-furanones can be prepared readily by 1,2-addition of organometallic compounds to γ,γ-disubstituted β-bromo-α,β-butenolides followed by treatment of the adducts with acid.     

A new strategy for construction of angularly fused tricyclic ring systems. Transannular bond formation of bicyclic enones via photochemical intramolecular hydrogen abstraction

Tricyclic ketones 3a, b and 7a–c having angularly fused 5-6-5 or 5-7-5 ring system have been efficiently prepared by irradiation of bicyclic enones 1 and 2.     

Gold-catalyzed highly efficient access to 3(2H)-furanones from 2-oxo-3-butynoates and related compounds

[reaction: see text] The gold-catalyzed cyclization reactions of 2-oxo-3-butynoic esters or disubstituted-1,2-diones with a variety of nucleophiles are described, which offer an efficient and straightforward route to substituted 3(2H)-furanones under mild reaction conditions. The Au(III) catalysts are also highly effective in the hydration of these activated alkynes.     

Functionalization of the pyridazin-3(2H)-one ring via palladium-catalysed aminocarbonylation

5-Iodo- and 4,5-dibromo-2-methylpyridazin-3(2H)-ones were aminocarbonylated in the presence of various amines including amino acid methyl esters in a palladium-catalysed reaction. The iodo derivative afforded the corresponding amides with complete conversion and high isolated yields. The dibromo derivative has shown unexpectedly high reactivity in this reaction, resulting in 4,5-dicarboxamides using primary amines as N-nucleophiles. Monoaminocarbonylation has not been observed, i.e., neither 4-bromo-5-carboxamide nor 4-carboxamido-5-bromo derivatives have been formed. However, the use of secondary amines such as piperidine and morpholine resulted in the formations of mixtures of amino-substituted bromopyridazinones. That is, no carbon monoxide insertion took place in these cases. Some mechanistic details of the formation of aminocarbonylation and amination products are also discussed.     

Transformation of alkyl esters of 4-oxo-3-phenylthioalkanoic acids into substituted 4-phenylthio-2(5H)-furanones and 3-phenylthiofurans

When the solutions of methyl and ethyl esters of 4-oxo-3-phenylthioalkanoic acids are boiled in toluene in the presence of p-toluene sulfonic acid, substituted 4-phenylthio-2(5H)-furanones are formed in good yields. In the reaction with diisobutylaluminum hydride or organomagnesium compounds, the latter convert into the corresponding 3-phenylthiofurans.Translated from Khimiya Geterotsiklicheskikh Soedinenii, Vol. 24, No. 3, pp. 313–316, March, 1988.     

Oxitranyl-Β-aminovinyl ketones. 2. Synthesis of 3(2H)-furanones

The reaction of oxiranyl--dimethylaminovinyl ketones with secondary amines, hydrochloric, and hydrobromic acids leads to the formation of the corresponding 2-aminomethyl- and 2-halomethyl-3-(2H)-furanones.For Communication 1, see [1].Translated from Khimiii Geterotsiklicheskikh Soedinenii, No. 12, pp. 1600–1603, December, 1988.Original article submitted May 20, 1987.     

Competitive reaction pathways of C2Cl3 + NO via four-membered ring and bicyclic ring intermediates

The products and mechanisms of the atmospherically and environmentally important reaction, C(2)Cl(3) + NO, are investigated comprehensively by step-scan time-resolved Fourier transform infrared emission spectroscopy and the CCSD(T)/6-311+G(d)//B3LYP/6-311G(d) level of electronic structure calculations. Vibrationally excited products of Cl(2)CO, ClNCO, CCl(3)NCO and NCO have been observed in the IR emission spectra. Cyclic intermediates are found to play important roles leading to the rich variety of the chemical transformations of the reaction. Mainly two competitive reaction pathways are revealed: the four-membered ring intermediate pathway leading to the products Cl(2)CO + ClCN which is essentially barrierless and the bicyclic ring intermediate pathway leading to the product channels of ClNCO + CCl(2,) CCl(3)NCO and CCl(3) + NCO which is rate-limited by a barrier of 42.9 kJ mol(-1) higher than the reactants. By photolyzing the precursor at 248 and 193 nm, respectively, C(2)Cl(3) radicals with different internal energy are produced to observe the product branching ratios as a function of reactant energy. The Cl(2)CO channel via the four-membered ring intermediate pathway is shown to be overwhelmingly dominant at low energy (temperature) but become less important at high energy while the ClNCO and CCl(3)NCO channels via the bicyclic ring intermediate pathway are greatly enhanced and compete effectively. The experimental observation of the products and their branching ratios varying with reactant energy is well consistent with the calculated potential energy profiles.     

A novel rearrangement of 2(5H)-furanones

A novel rearrangement of 2(5H)-furanones is described. When refluxed in aq. Ethanolic solution in the presence of excess KOH, the 2,5-dihydro-2-oxofuran-3-carboxamides 6 underwent a novel rearrangement to the corresponding 4,5-dihydro-4-oxo-2-(phenylamino)-3-furancarboxylic acids 1 in moderate-to-excellent yields.     

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.     

Cycloisomerization of bifunctionalized allenes: synthesis of 3(2H)-furanones in water

A simple protocol for the efficient synthesis of 3(2H)-furanones by cycloisomerization of allenic hydroxyketones is described. This transformation is achieved in water and in the absence of any expensive metal catalysts.     

Synthesis and stereochemistry of 2-benzylidene-4-carbethoxy-5-methyl-3-(2H)-furanones

The title products were obtained by Knoevenagel condensation between 4-carbethoxy-5-methyl-3-(2H)furanone and substituted benzaldehydes (or 4-chloroacetophenone). The configuration of the resulting compounds was investigated by ¹H nmr using the lanthanide shift reagent.