Unexpected deprotection of silyl and THP ethers induced by serious disparity in the quality of Pd/C catalysts and elucidation of the mechanism

Autor:	Takashi Ikawa, Kosaku Hirota, Hironao Sajiki
Rok vydání:	2004
Předmět:	Silylation Hydrogen Organic Chemistry chemistry.chemical_element Cleavage (embryo) Biochemistry Medicinal chemistry Silyl ether Catalysis chemistry.chemical_compound chemistry Palladium on carbon Drug Discovery Organic chemistry Solvolysis Ether cleavage
Zdroj:	Tetrahedron. 60:6189-6195
ISSN:	0040-4020
DOI:	10.1016/j.tet.2004.05.040
Popis:	Commercial Pd/C catalysts show different catalytic activity toward the deprotection of silyl and THP ethers. The Pd/C purchased from Merck and ACROS exhibits marked tendency to cleave these protective groups unexpectedly without hydrogen conditions although Aldrich's Pd/C (20,569-9) is inactive in the absence of hydrogen. It was proved that the Pd/C disparity toward the deprotection of TES and THP ethers results from residual acids and/or palladium chloride in the production process of Pd/Cs. Although a TES ether cleavage reaction in the absence of hydrogen and a THP ether cleavage reaction in the presence of hydrogen using 10% Pd/C were recently published, we could conclude they were only an acid-catalyzed solvolysis, the acid being released from the catalyst. Hydrogen is essential for the actual 10% Pd/C-catalyzed cleavage of TES ethers and THP ethers which must be stable under the true Pd/C-catalyzed hydrogenation conditions.
Databáze:	OpenAIRE
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