Synthesis of butenolides
Various α-substituted butenolides were efficiently prepared from 3-bromo-2-triisopropylsilyloxyfuran via lithium-bromine exchange and subsequent derivatization with carbon or heteroatom electrophiles. A short and efficient synthesis of an anti-inflammatory lipid, isolated from a marine gorgonian, is described.
J. Boukouvalas, R. P. Loach, J. Org. Chem., 2008, 73, 8109-8112.
4-tosyl-2(5H)-furanone is easy to prepare in excellent yield and more stable than the corresponding triflate. A palladium catalyzed reaction between 4-tosyl-2(5H)-furanone and boronic acids gives 4-substituted 2(5H)-furanones.
J. Wu, Q. Zhu, L. Wang, R. Fathi, Z. Yang, J. Org. Chem., 2003, 68, 670-673.
An oxidative cyclization of β-substituted β,γ-unsaturated carboxylic acids using a hypervalent iodine reagent provides 4-substituted furan-2-ones. The use of the highly electrophilic PhI(OTf)2, which is in situ prepared from PhI(OAc)2 and Me3SiOTf, is crucial. Depending on the substitution pattern at the α-position of the substrates, furan-2(5H)-ones or furan-2(3H)-ones are produced.
K. Kiyokawa, K. Takemoto, S. Yahata, T. Kojima, S. Minakata, Synthesis, 2017, 49, 2907-2912.
The mild, palladium-catalyzed reaction of arenediazonium tetrafluoroborates with methyl 4-hydroxy-2-butenoate in MeOH gives 4-arylbutenolides in good yields through a domino vinylic substitution/cyclization process. The reaction tolerates halogen substituents, nitro, ether, cyano, keto, and ester groups and can be performed as a one-pot process generating the arenediazonium salt in situ.
S. Cacchi, G. Fabrizi, A. Goggiamani, A. Sferrazza, Synlett, 2009, 1277-1280.
A chiral electrophilic selenium catalyst based on a rigid indanol scaffold, which can be easily synthesized from a commercially available indanone, efficiently converts β,γ-unsaturated carboxylic acids into various enantioenriched γ-butenolides under mild conditions.
Y. Kawamata, T. Hashimoto, K. Maruoka, J. Am. Chem. Soc., 2016, 138, 5206-5209.
The ruthenium-catalyzed ring-closing metathesis of methallyl acrylates gave 4-Methyl-5-alkyl-2(5H)-furanones in good to high yields. Despite the electron deficiency of both double bonds in the starting acrylates, the first-generation Grubbs' catalyst proved to be an effective catalyst for the ring closure.
M. Bassetti, A. D'Annibale, A. Fanfoni, F. Minissi, Org. Lett., 2005, 7, 1805-1808.
The combination of the carbophilic Lewis acidity of Au with the redox properties of Pd enabled the preparation of a variety of substituted butenolides in a simple and efficient way. The Au-Pd bimetallic catalytic system is based on the generation of competent Au and Pd species by anionic ligand exchange.
P. García-Domínguez, C. Nevado, J. Am. Chem. Soc., 2016, 138, 3266-3269.
A Pd-catalyzed arylation of butenolides with high selectivity for the γ-position allows a facile construction of quaternary centers. The preparation of a wide variety of γ-aryl butenolides containing a number of functional groups is outlined.
A. M. Hyde, S. L. Buchwald, Org. Lett., 2009, 11, 2663-2666.
A combination of Lewis and Brønsted acids enables an efficient and practical approach to highly substituted butenolides via the annulation of keto acids and tertiary alcohols. Various highly substituted butenolides are readily produced in synthetically useful yields.
W. Mao, C. Zhu, Org. Lett., 2015, 17, 5710-5713.
A new and convenient one-pot catalytic addition-elimination reaction converted a range of (E)-3-butenoic acids into the corresponding butenolides in good yields in the presence of 5 mol % diphenyl diselenide and [bis(trifluoroacetoxy)iodo]benzene in acetonitrile.
D. M. Browne, O. Niyomura, T. Wirth, Org. Lett., 2007, 9, 3169-3171.
An AgOTf-catalyzed intramolecular cyclization of phenoxyethynyl diols affords multisubstituted α,β-unsaturated-γ-lactones in good yields under mild conditions. This method was also applicable to the synthesis of α,β-unsaturated-δ-lactones. Replacement of AgOTf with a stoichiometric amount of N-bromosuccinimide furnishes α-bromo-substituted α,β-unsaturated lactones.
M. Egi, Y. Ota, Y. Nishimura, K. Shimizu, K. Azechi, S. Akai, Org. Lett., 2013, 15, 4150-4153.
An exclusive 6-endo-dig iodocyclization of 3-ethoxy-1-(2-alkoxyphenyl)-2-yn-1-ols gives 4-substituted 3-iodocoumarins, whereas a 5-endo-dig iodocyclization of 1-alkoxy-4-ethoxy-3-yn-1,2-diols gives 3-iodobutenolides respectively. The reactions are carried out under very mild conditions using I2 in DCM or toluene at room temperature.
M. S. Reddy, N. Thirupathi, M. H. Babu, S. Puri, J. Org. Chem., 2013, 78, 5878-5888.
A Cu(II)-catalyzed acylation of acyloins with a thiol ester present in Wittig reagents under neutral conditions through a push-pull mechanism enables a one-pot lactonization to yield butenolides. The synthetic utility of this method for the synthesis of natural products is shown.
K. Matuso, M. Shindo, Org. Lett., 2010, 12, 5346-5349.
A mild copper-catalyzed [2 + 3] formal cyclization reaction between α-hydroxyl ketones and arylacetonitriles provides butenolides or oxazoles depending on the structure of the α-hydroxy ketones employed. Whereas tertiary α-hydroxy ketones furnished 3,4,5,5-tetrasubstituted butenolides selectively, secondary α-hydroxy ketones gave 2,4,5-trisubstituted oxazoles as the sole products.
C. Qi, Y. Peng, L. Wang, Y. Ren, H. Jiang, J. Org. Chem., 2018, 83, 11926-11935.
A sequential rhodium-catalyzed addition/lactonization reaction of organoboron derivatives to alkyl 4-hydroxy-2-alkynoates allows the synthesis of 4-aryl/heteroaryl/vinyl-2(5H)-furanones with an excellent control of regio- and chemoselectivity.
M. Alfonsi, A. Arcadi, M. Chiarini, F. Marinelli, J. Org. Chem., 2007, 72, 9510-9517.
Cyclic organometallic intermediates formed via CuCl-mediated highly regio- and stereoselective carbomagnesiation of 2,3-allenols with Grignard reagents smoothly react with carbon dioxide to afford 2(5H)-furanones. The reaction with organomagnesium chlorides proceeded smoothly under mild conditions to afford the products in very good yields due a dramatic effect of the halide anion from the Grignard reagent for CO2 activation.
S. Li, B. Miao, W. Yuan, S. Ma, Org. Lett., 2013, 15, 977-979.
A boron-catalyzed aldol reaction of pyruvic acids with aldehydes in water at room temperature delivers useful isotetronic acid derivatives in high yields. Both boronic and borinic acids function as catalysts, with the latter demonstrating particularly high activity. A wide range of aldehydes, including enolizable species, may be employed.
D. Lee, S. G. Newman, M. S. Taylor, Org. Lett., 2009, 11, 5486-5489.
Tetronic acids substituted by various groups were synthesized in one pot from the corresponding aryl- or heteroarylacetic acid esters and hydroxyacetic acid esters, by a tandem process involving a transesterification and a subsequent Dieckmann cyclization.
A. Mallinger, T. Le Gall, C. Mioskowski, Synlett, 2008, 386-388.
A one-pot, convenient and general access to 5-sp2-substituted and 5,5-disubstituted tetronic acids embodies two consecutive chemical events: a Michael addition of pyrrolidine on a secondary or tertiary γ-hydroxy-α,β-alkynyl ester derivative to give the corresponding enamine, and a subsequent acid-catalyzed hydrolysis-lactonization.
D. Tejedor, A. Santos-Expósito, F. García-Tellado, Synlett, 2006, 1607-1609.
A highly efficient carbon-carbon triple bond cleavage reaction of (Z)-enynols offered a new route to highly substituted butenolides through a gold(I)-catalyzed tandem cyclization/oxidative cleavage.
Y. Liu, F. Song, S. Guo, J. Am. Chem. Soc., 2006, 128, 11332-11333.
γ-Methylene-α,β-unsaturated γ-lactones were efficiently synthesized by a Pd-catalyzed cyclization of 3,4-alkadienoic acids. The use of a N2 atmosphere ensures a high purity of the products.
S. Ma, F. Yu, Tetrahedron, 2005, 61, 9896-9901.
An efficient gold(I)-catalyzed carbocyclization reaction enables the synthesis of isomycin derivatives from propargyl diazoacetates. The use of protic additives was essential to regulating the reaction outcome by fine-tuning the catalytic preference of the gold(I) complex.
M. Bao, X. Wang, L. Qiu, W. Hu, P. W. H. Chan, X. Xu, Org. Lett., 2019, 21, 1813-1817.
A highly efficient Cu(I)-catalyzed addition/annulation sequence enables the synthesis of (Z)-ylidenebutenolides from readily available α-ketoacids and alkynes. The reaction displays good substrate scope, and delivers products with high stereoselectivity. The ylidenebutenolides can be converted into a diverse range of heterocycles.
S. Seo, M. C. Willis, Org. Lett., 2017, 19, 4556-4559.
A biomimetic proton transfer catalysis with a chiral organic catalyst enabled an enantioselective olefin isomerization of a broad range of mono- and disubstituted β,γ-unsaturated butenolides into the corresponding chiral α,β-unsaturated butenolides in high enantioselectivity and yield. Mechanistic studies have revealed the protonation as the rate-determining step.
Y. Wu, R. P. Singh, L. Deng, J. Am. Chem. Soc., 2011, 133, 12458-12461.
An efficient copper-catalyzed sulfenylation and selenylation of 2,3-allenoic acids with disulfides or diselenides afford various 4-sulfenylated and 4-selenylated butenolides in good yields via tandem radical addition/intramolecular cyclization processes. Moreover, 4-sulfonylated butenolides could also be obtained by sulfenylation of 2,3-allenoic acids and subsequent oxidation.
Y.-X. Xin, S. Pan, Y. Huang, X.-H. Xu, F.-L. Qing, J. Org. Chem., 2018, 83, 6101-6109.