SELECTIVE CLEAVAGE OF ETHERS USING SILICA-ALUMINA GEL CATALYSTS PREPARED BY THE SOL-GEL METHOD

The selective cleavage of tetrahydropyranyl (THP), methoxymethyl (MOM) , 1-ethoxyethyl (EE), 1-methyl-1-methoxyerhyl (MME) and trimethylsilyl (TMS) ether groups with silica-alumina gels prepared by the sol-gel m ethod has been investigated The deprotection rate follows the order: T MS > MME >> EE > THP >> MOM. The selective deprotection of diol deriva tives with mixed protecting groups was achieved efficiently. Bis-THP a nd bis-MOM ether derivatives of a substrate which contained a primary and a tertiary hydroxyl groups were mono-deprotected with moderate sel ectivity. The selective deprotection of glycerol ethers was also exami ned. The silica-alumina gels prepared by the sol-gel method are thus s hown to be a good catalyst for selective cleavage of ether protecting groups giving the product in a simple manner under mild conditions. Co pyright (C) 1996 Published by Elsevier Science Ltd