Deprotection of THP ethers

Procedures for deprotection of THP-ethers. Use of methanolic hydrochloric acid. The THP-ether (0.2 mol) was dissolved in methanol (200ml) and concentrated hydrochloric acid (30 ml), and the mixture heated under reflux for 2 hours. After cooling, the solution was neutralised by the addition of an excess of sodium hydrogen carbonate, diluted with ether (200 ml), filtered and the ether evaporated. The residue was dissolved in ether, washed twice with water, dried and evaporated. The deprotected alcohol was distilled under reduced pressure. 

The tetrahydropyranylation of alcohols under solvent-free conditions is catalyzed by bismuth triflate as well (Equation (8.11)). The catalyst is insensitive to air and small amounts of moisture, easy to handle, and relatively nontoxic. The deprotection of THP ethers is also catalyzed by bismuth triflate [29]. 

Wang Y-G, Wu XX, Jiang Z-Y (2004) A mild and effcient selective tetrahydropyranylation of primary alcohols and deprotection of THP ethers of phenols and alcohols using PdCl2(CH3CN)2 as catalyst. Tetrahedron Lett 45 2973-2976... 

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