An Unexpected Iodine‐Mediated Reaction of 2‑Mercaptobenzoxazoles with Bicyclic Amidines and Methyl Ketones. Novel Route Toward 5‑Sulfenyl‐2‐Iminothiazolines

Abstract A facile and straightforward route toward 5‑sulfenyl‐2‐iminothiazolines bearing ε‐caprolactam or γ‐lactam was serendipitously discovered. In attempts to achieve α‐sulfenylation of methyl ketones with 2‐mercaptobenzoxazoles using iodine and bicyclic amidine bases (DBU or DBN) as activators, bis‐sulfenylated enamines derived from the participation of the amidines as nucleophiles were unexpectedly formed. Further intramolecular cyclization of these α‐dithioenamines with concomitant oxazole ring opening provides a convenient means to access structurally diverse 5‐sulfenyl‐2‐iminothiazolines.