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.
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.
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.
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 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.
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 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.
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.
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.