Amberlyst 15-Catalyzed Efficient Synthesis of 5-Acetyl-4-hydroxy-coumarone and 5-Acetyl-6-hydroxy-coumarone: Crucial Precursors for Several Naturally Occurring Furanoflavones
Amberlyst 15-Catalyzed Efficient Synthesis of 5-Acetyl-4-hydroxy-coumarone and 5-Acetyl-6-hydroxy-coumarone: Crucial Precursors for Several Naturally Occurring Furanoflavones
A wide variety of alcohols, phenols and amines are efficiently and selectively converted into the corresponding acetates by treatment with acetic anhydride in the presence of catalytic amounts of La(NO3)3·6H2O undersolvent-freeconditions at room temperature. The method is compatible with acid sensitive hydroxyl protecting groups such as TBDMS, THP, OBz, OBn, Boc and some isopropylidenes and offers
Benzofurans functionalized with hydroxy and acetyl functionalities are not only the core structures found in a large number of biologically important natural products, but also the vital precursors for several naturally occurring furanoflavonoids. Numerous synthetic methodologies are available in the literature for the synthesis of functionalized benzofurans but access to benzofurans with adjacent hydroxy and acetyl functionalities shows paucity of references. In this paper we report highly convenient synthesis of nature-mimicking benzofurans and their dimers from easily accessible precursors.
Total synthesis of naturally occurring moracinflavan E and related compounds
作者:Ting-Yu Lin、Chieh-Yu Chou、Yu-Hsuan Chen、Chien-Kuo Ku、Ming-Jaw Don
DOI:10.1016/j.phytol.2022.05.011
日期:2022.8
A total synthesis of four flavans with a furan ring in different positions (1–4) was achieved successfully. The flavan was synthesized from flavanone by reduction and followed by deoxygenation steps. The synthesized compound 2 was confirmed as the naturallyoccurring moracinflavan E based on the comparison of their NMR spectral data.
Novel synthesis of rotenoid, pongarotene, by oxidative rearrangement using thallium(III) <i>p</i>-tosylate
作者:Chidvilas Kurapati、Om V. Singh、Rambabu Gundla
DOI:10.1080/00397911.2022.2079990
日期:2022.4.18
Abstract The synthesis of furano-rotenoid, pongarotene, by oxidative 1,2-aryl rearrangement of the sprirochromanone (11) using thallium(III) p-tosylate as key step has been described. Pongarotene (12) structure was confirmed by 2D NMR, HRMS and finally by X-ray crystallography. The sprirochromanones were synthesized by radical cyclization of chromone derivative (10). This methodology will be useful
5-carbonyl-4-hydroxybenzofurans via a phenol-directed intramolecular Friedel–Crafts reaction. This synthetic method was applied for the total synthesis of furanoflavones. Experimental studies and density functional theory calculations suggest that hydrogen bond interactions between the phenolic hydroxy group and the scandium complex realize regioselective intramolecular cyclization.