This project involves the application of two facile cyclization systems for the development of redox-sensitive protecting groups for organic synthesis. The feasibility of applying such facile cyclization systems in peptide synthesis will also be studied. Because the facile cyclization systems are cleaved under mild reductive conditions, they can be selectively removed without affecting other functional groups commonly seen in organic compounds and peptides. Therefore, this provides a protecting strategy, which is orthogonal to other methods available. Efforts will he focused on testing the practical feasibility of applying these two facile cyclization systems in organic and peptide syntheses.