A novel sodium iodide-promoted ring transformation of 2-amino-4,5-dihydro-3-furancarbonitriles to 2-pyrrolidinones and dihydropyrans

A novel and efficient approach to 2-pyrrolidinones and dihydropyrans via the ring transformation of 3-phenacylated tetrahydro-2-imino-3-furancarbonitriles in the presence of sodium iodide is described. The key feature in the ring transformation is that C-phenacylation of 2-amino-4,5-dihydro-3-furancarbonitriles using phenacyl bromides, e.g. phenacyl bromide, 4-chlorophenacyl bromide and 4-methoxyphenacyl bromide, proceeds smoothly and the ring-opening intermediate having leaving group such as iodide ion is produced.