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p-Methoxybenzyl ether cleavage by polymer-supported sulfonamides
Ronald J Hinklin1, Laura L Kiessling
1Departments of Chemistry and Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
Organic Letters
|April 2, 2002
Summary
A new method efficiently removes p-methoxybenzyl protecting groups from alcohols using catalytic trifluoromethanesulfonic acid. This protecting group strategy is effective both in solution and on safety-catch resins.
Area of Science:
- Organic Chemistry
- Synthetic Chemistry
- Protecting Group Chemistry
Background:
- p-Methoxybenzyl (PMB) ethers are commonly used protecting groups in organic synthesis.
- Efficient and selective deprotection methods are crucial for complex molecule synthesis.
Purpose of the Study:
- To develop a novel method for the cleavage of p-methoxybenzyl ethers.
- To investigate the transfer of p-methoxybenzyl groups to sulfonamides as a deprotection strategy.
Main Methods:
- Utilizing catalytic amounts of trifluoromethanesulfonic acid (TfOH) in solution.
- Employing sulfonamide-functionalized "safety-catch" resins for solid-phase synthesis applications.
Main Results:
- Demonstrated efficient transfer of p-methoxybenzyl ethers from alcohols to sulfonamides.
- Achieved high yields (>94%) for solution-phase deprotection.
- Obtained excellent yields with minimal purification when using safety-catch resins.
Conclusions:
- Triflic acid-catalyzed PMB ether cleavage offers a robust and high-yielding deprotection method.
- The developed method is versatile, applicable in both solution and solid-phase synthesis.
- This approach simplifies purification, enhancing its utility in complex synthetic routes.