Solid-Supported Acids for Debenzylation of Aryl Benzyl Ethers

Abstract

Solid-supported acids have been investigated for aromatic debenzylation reactions. Stoichiometric amounts of solid-supported acids in refluxing toluene with or without 4 equiv of methanol effectively provided the desired aromatic debenzylation products of various systems in moderate to excellent yields (up to 98%).

Acidic rearrangement of benzyl group in flavone benzyl ethers and its regioselectivity

“…Rearrangement to the flavone B ring from the flavone A ring is also possible (the benzyl group of compound 2 rearranged from position 5 to position 6 0 ). This is different from the regioselectivities previously reported for simple aromatic compounds and flavanone compounds, in which the rearrangement of a benzyl group mainly occurred on the ortho and para positions, and ortho rearrangement dominated [10,12]. This may be because previous systems were relatively simple, and the flavone compound system with four substituted groups used here is relatively complicated.…”

“…A reaction mechanism for the acidic rearrangement of the benzyl group in aromatic benzyl ether compounds was proposed by some researchers, based the observation of the intermolecular benzylated product [10,12]. According to this reaction mechanism (Scheme 2), the flavone benzyl ethers were first protonated under the conditions of methylsulfonic acid (MSA) to form free debenzylated flavones and benzyl cation.…”

“…The rearrangement reaction of benzyl groups can be observed in the debenzylation of aryl benzyl ethers, and the related reactions observed in previous reports are mainly involving simple aromatic compounds and aromatic amino compounds [10,11]. Recently, this reaction was successfully used by the Seoane group and us to totally synthesize benzyl-substituted flavone compounds and benzyl-substituted flavanone compounds [9,12].…”

Syntheses, spectroscopic and crystallographic characterizations of 4-nitrobenzyloxy derivatives and benzofurans from ortho-substituted benzaldehydes and 4-nitrobenzyl bromide

“…The compounds (2 and 3) were successfully synthesized with yields in the range 44-48% (Scheme 2a). Compound 1 was synthesized according to the previously published procedure [28][29][30] by using different solvents and bases in the reactions.…”

Acidic Rearrangement of (Benzyloxy)chalcones: A Short Synthesis of Chamanetin

“…The reaction is known for simple phenols and aromatic amino acids, but not for flavonoids. [31][32][33][34][35] To determine the preparative value of this reaction of benzyl phenyl ethers, we decided to re-examine the rearrangement of (benzyloxy)benzene (14) in the presence of trifluoroacetic acid (Scheme 2). Treatment of 14 with trifluoroacetic acid in refluxing chloroform gave mixtures of 2-benzylphenol (15) phenol (16), and 4-benzylphenol, 17.…”