Synthesis of cyclic ether-N-benzyl glycine polypeptides based on single electron transfer-promoted photocyclization processes

Abstract

Exploratory photochemical studies on trimethylsilyl-terminated phthalimide-ether-N-benzylpolyglycines in which phthalimides worked as light absorbance acceptors and ether-N-(trimethylsilyl)methylamides served as electron donor centers have been conducted, leading to the development of new synthetic methodology to construct cyclic polypeptide mimetics. It was found that irradiation on trimethylsilyl-terminated phthalimide-ether-poly-N-benzylglycine 5a~5f in methanol led to efficient generation of cyclic peptide products 6a~6f, which may be through sequential single electron transfer (SET) pathway. The structures of these cyclic peptide products were determined by NMR and HRMS spectroscopy as well as fully characterized by X-ray crystallography. © 2013 Chinese Chemical Society & SIOC, CAS.