A Four-Step Total Synthesis of Radermachol

Abstract

Radermachol has been synthesized in four steps and an overall yield of 22% via key ytterbium triflate catalyzed furannulation and intramolecular nucleophilic acylation reactions.

A Mild and Versatile Friedel–Crafts Methodology for the Diversity‐Oriented Synthesis of Redox‐Active 3‐Benzoylmenadiones with Tunable Redox Potentials

“…As such, 2‐benzoyl‐NQs have been reported as key intermediates for the synthesis of 7 H ‐benzo[ c ]xanthen‐7‐ones, or advanced precursors to obtain the complex polycyclic 1,4‐dioxygenated xanthone aglycone, IB‐00208 . These key moieties have also led to a smart strategy in the total four‐step synthesis of the naturally occurring red pigment radermachol, improving the previous synthetic scheme…”

“…[9] As such, 2-benzoyl-NQs have been reported as key intermediates for the syn- thesis of 7 H-benzo[c]xanthen-7-ones, [10] or advanced precursors to obtain the complex polycyclic1 ,4-dioxygenatedx anthone aglycone, IB-00208. [9] These key moieties have also led to as mart strategy in the total four-step synthesis of the naturally occurring red pigment radermachol, [11] improvingt he previous synthetic scheme. [12] One of the strategies to build 2-benzoyl-1,4-naphthoquinone moieties is based on the generation of 2-benzoyl-1,4-dihydronaphthalene;t his hydroquinone is readily oxidized into the target quinone moiety.P hoto-Friedel-Crafts acylation of NQs with al arge stoichiometric excesso fa romatic aldehydes provided the 2-benzoyl-dihydronaphthalene derivatives (Scheme 1).…”

“…Most of the cited methodologies required dry conditions, high temperatures, or pre‐activation of the reagents. Nevertheless, noticeable progress has been made by using trifluoroacetic anhydride (TFAA) or trifluoroacetic acid/trifluoroacetic anhydride (TFA/TFAA), under mild heating conditions and air moisture, to allow the S E Ar of activated and non‐strong deactivated benzoic acids, depending on the nucleophilic strength of the aromatic compound.…”

A versatile Diels–Alder approach to functionalized hydroanthraquinones

“…The studies were initiated with the straightforward synthesis of highly activated quinones by modifying a procedure developed by Buccini & Piggott [34]. The three-step synthesis provided 2-(2iodobenzoyl)naphthalene-1,4-dione 5a in excellent yield (scheme 1).…”

$$\hbox {Re}_{2}\hbox {O}_{7}$$ Re 2 O 7 -catalyzed formal [3 + 2] cycloaddition for diverse naphtho[1,2-b]furan-3-carboxamides and their biological evaluation

“…Radermachol (5) was isolated from Radermachera xylocarpa K. Schum in India [13,14], and it has been used as nervine, calmative, antispasmodic, emetic, anthelmintic, abortifacient, as well as a substitute for ipecacuanha [13,14]. The structure of compound 5 was established by spectroscopic analysis and X-ray crystallography [13,14], and its total synthesis was reported by several groups [15][16][17][18]. Compound 6, a synthetic furomollugin analog, significantly inhibited tumor necrosis factor (TNF)-α-induced inflammatory responses in HT-29 human colon epithelial cells and might be a valuable new drug candidate for the treatment of colon inflammation [19].…”