Reactions with thioethoxide ion in dimethylformamide. I. Selective demethylation of aryl methyl ethers

Abstract

Recent methods for demethylating aryl methyl ethers have been briefly reviewed, especially methods involving the use of nucleophilic reagents. Sodium thioethoxide dissolved in N,N-dimethylformamide has been developed as a powerful new reagent for demethylating aryl methyl ethers cleanly and rapidly in high yield. The reaction conditions can be controlled so that aromatic bromo substituents or isolated olefinic bonds are unaffected. Of special interest has been the selective monodemethylation of the methyl ethers of di- and tri-hydric phenols, exemplified by the isolation in high yield of orcinol monomethyl ether, p-methoxyphenol, guaiacol, and phloroglucinol dimethyl ether from the respective fully O-methylated compounds. An exception was pyrogallol trimethyl ether which afforded pyrogallol 1-monomethyl ether in high yield.

Attempt to Synthesize 2,3,5,4′-Tetrahydroxystilbene Derived from 2,3,5,4′-Tetrahydroxystilbene-2-<i>O</i>-β-glucoside (THSG)

“…Furthermore, demethylation of aromatic methyl ether with trimethysilyl iodide and pyridine in CH 2 Cl 2 at −78°C or with sodium isopropyl thiolate in DMF at reflux did not give the aglycone 1. 29) This appeared to confirm the sensitivity of phenolic functional groups such as those in THSG to these reaction conditions. The presence of the second hydroxyl group in the ortho or para position is speculated to be due to its isomerization to o-quinone or p-quinone derivatives.…”

“…The key step in the synthesis of the aglycone 1 is to form the stilbene via the MizorokiHeck reaction. 29) A palladium-catalyzed Mizoroki-Heck reaction has been also used previously to form resveratrol, glucopyranosides of resveratorol and polymethoxystilbenes. 2,30,31) In our strategy, we used the Mizoroki-Heck reaction of a .…”

Tandem Wessely oxidation and intramolecular Diels–Alder reactions. III. Synthesis of isotwistanes

“…Resort was therefore had to demethylation of 9 and 10 under basic conditions with sodium thioethoxide in dimethylformamide (12) tively? Reduction of 18 with lithium tri-(tert-butoxy)aluminum hydride (14) or sodium bis(2-methoxyethoxy)aluminum hydride (REDAL) plus one equivalent of ethanol (15) has previously been reported to give 21 in yields of 50%.…”

Oxilorphan and Butorphanol. Potent Narcotic Antagonists and Nonaddicting Analgesics in the 3,14-Dihydroxymorphinan Series. Part V

“…Alternatively 7e was demethylated with pyridine hydrochloride, and 7k with sodium ethylthiolate (6). Demethylation of 7i with boron tribromide led to partial hydration of the double bond, and in addition to the expected unsaturated base 8h, we also obtained some trio1 8i.…”