Maleic anhydrides in synthesis. Preparation of furan-2(5H)-one phosphonate derivatives and a new synthesis of pulvinic acids and pulvinone analogues

Abstract

Reactions between substituted maleic anhydrides, viz. 1, and sodium dimethyl phosphite in refluxing benzene are shown to lead to the corresponding furan-2(5H) -one phosphonates 2 and 8. Wadsworth-Emmons olefination reactions involving 2 and heteroarylaldehydes and arylbenzoyl formates 14 then provides a n e w synthesis of heterocyclic analogues of pulvinones, i.e. 10-1 3, and of permethylated pulvinic acids, e.g. 16-17 which are found in higher fungi.

Norbadione A: Synthetic Approach to the Bis(pulvinic acid) Moiety and Cesium‐Complexation Studies

“…A Suzuki–Miyaura reaction of triflate 5 was then carried out using phenylboronic acid in the presence of the catalyst [Pd(PPh 3 ) 4 ] and the base K 3 PO 4 at reflux in dioxane,11 to afford compound 10 in 86 % yield (Scheme ). The 1 H NMR spectrum of compound 10 was identical to that reported for the E isomer of O ‐methylisopinastric acid, which is quite different from that of the Z isomer 12. This allowed us to determine the E configuration of the central double bond in alcohol 9 unambiguously.…”

Synthesis of Pulvinic Acid and Norbadione A Analogues by Suzuki–Miyaura Cross‐Coupling of Benzylated Intermediates

“…Melting points are uncorrected. NMR: 300.13 MHz for 1 H, 75.47 MHz MHz for 13 C. Chemical shifts (δ) are in ppm; coupling constants (J) are in Hz.…”

“…Analogous conditions applied to triflate 5a therefore allowed the preparation of the pulvinic acid derivative 15 in 86 % yield. Comparison of the physical and spectroscopic data of compound 15 with the values reported for both stereoisomers, which had been previously synthesized, [13] allowed the unambiguous assignment of the (E) configuration for this compound. The cleavage of the methyl protecting groups of pulvinic acid derivative 15 with iodotrimethylsilane has been described previously.…”

“…The cleavage of the methyl protecting groups of pulvinic acid derivative 15 with iodotrimethylsilane has been described previously. [13] Under analogous conditions, we obtained mixtures of partially and fully deprotected pulvinic compounds. We thus preferred to carry out the syntheses of other pulvinic compounds from triflate 5b, in which the enol and phenol functions are protected as benzyl ethers.…”

Tetramic and Tetronic Acids as Scaffolds in Bioinorganic and Bioorganic Chemistry

“…On the other hand, tetronic acids, 4-hydroxy-[5H] furan-2-ones, are compounds with antibiotic, antiviral, antineoplastic, and anticoagulant activity [ 10 , 11 ]. Compounds which have been isolated from natural products and exhibit such activity are tetronasin [ 12 ], RK-682 [ 2 , 13 ], the well-known family of compounds named vulpinic acids [ 14 , 15 ] and many others.…”