Unified Approach to Furan Natural Products via Phosphine‐Palladium Catalysis

Abstract

Polyalkyl furans are widespread in nature,o ften performing important biological roles.D espite ap lethora of methods for the synthesis of tetrasubstituted furans,t he construction of tetraalkylf urans remains non-trivial. The prevalence of alkylgroups in bioactive furan natural products, combined with the desirable bioactivities of tetraalkylf urans, calls for ageneral synthetic protocol for polyalkylfurans.This paper describes aM ichael-Heck approach, using sequential phosphine-palladium catalysis,f or the preparation of various polyalkylf urans from readily available precursors.T he versatility of this method is illustrated by the total syntheses of nine distinct polyalkylated furan natural products belonging to different classes,n amely the furanoterpenes rosefuran, sesquirosefuran, and mikanifuran;the marine natural products plakorsins A, B, and Dand plakorsin Dmethyl ester;and the furan fatty acids 3D5 and hydromumiamicin.

Electrochemically-mediated C–H functionalization of allenes and 1,3-dicarbonyl compounds to construct tetrasubstituted furans

“…6,7 These valuable tetrasubstituted furan derivatives can be synthesized by two methods: one is the functionalization of existing furan rings, 8,9 and the other is the cyclization of acyclic substrates to construct furan rings. [10][11][12][13][14] Although the functionalization of furans seems to be an attractive approach, significant challenges remain in terms of reaction scope and chemoselectivity. The classical synthesis methods for tetrasubstituted furans include Paal-Knorr cyclocondensation (from 1,4-dicarbonyl compounds) 15,16 and Feist-Bénary cyclocondensation (from α-haloketones and β-dicarbonyl compounds).…”

Catalytic Enantioselective Reactions of Biomass-Derived Furans

“…These platform chemicals can be easily transformed into value-added chemicals, such as 2-methylfuran, 2,5dimethylfuran, and other furans via chemical conversions or fermentation [4][5][6]. Since aromatic heterocycle furans are present in a variety of chiral natural products, pharmaceuticals, and other intermediates, a plethora of enantioselective methodologies has been developed for the synthetic community [7][8][9]. The important strategies are given as follows-(i) enantioselective cyclization reactions including cycloadditions using furans as the 4π diene component and cyclopropanation between furan and diazoester to obtain various valuable chiral synthons (Section 2); (ii) enantioselective Friedel-Crafts cycloadditions for the fabrication of carboncarbon bonds between furans and electron-deficient alkenes, yielding chiral centers at the α-orβ-position of furans (Section 3); (iii) various enantioselective nucleophilic addition reactions of furfural as an electrophile for the construction of chiral hydroxyl functional groups (Section 4).…”

Phosphine-Catalyzed Synthesis of 3-Allyl-4-pyrones by the Tandem Reaction of Diynones and Allylic Alcohols

“…However, the preparation of functionalized allyl-4-pyrones has large challenge under metal-free condition, possibly due to the lack of suitable substrates. Inspired by the reaction of ynones with allylic alcohols and our successful transitions of ynones, we envisioned that 3-allyl-4-pyrones may be easily prepared from diynones and allylic alcohols through a tandem cyclization reaction under metal-free condition (Scheme d). Herein, we first reported a simple and efficient synthesis of 3-allyl-4-pyrones from diynones and allylic alcohols with high regioselectivity, broad substrate tolerance, and atom economy under metal-free condition.…”