Triarylamminium Radical Cation Facilitates the Deprotection of tert-Butyl Groups in Esters, Ethers, Carbonates, and Carbamates
Denisa Hidasová and Tomáš Slanina*
*Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo nám. 2, 166 10 Prague, Czech Republic,
Email: tomas.slanina
uochb.cas.cz
D. Hidasová, Tomáš Slanina, J. Org. Chem., 2023, 88, 6932-6938.
DOI: 10.1021/acs.joc.3c00238
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Abstract
The combination of the tris-4-bromophenylamminium radical cation, commonly known as magic blue (MB•+), and triethylsilane mediates a mild OtBu deprotection. Magic blue catalytically facilitates the cleavage of the C-O bond in tert-butyl carbamates, carbonates, esters, and ethers in a high isolated yield under mild conditions, and sacrificial triethylsilane accelerates the reaction.
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de-tert-butylation of a complex substrate
proposed mechanism
General procedure for deprotection of tert-butyl groups in esters, ethers, carbonates, and carbamates:
To a solution of tert-butylated compound (0.34 mmol, 1.0 equiv) in dry dichloromethane (3 mL), triethylsilane (0.68 mmol, 2.0 equiv) was added, followed by tris-4-bromophenylamminium cation radical (0.17 mmol, 0.5 equiv). The resulting mixture was stirred at room temperature until the starting material was consumed as indicated by TLC. The mixture was evaporated, and the residue was purified by column chromatography, which gave the desired product.
Key Words
tert-butyl esters, tert-butyl ethers, tert-butyl carbamates, triethylsilane
ID: J42-Y2023
