A new practical route to chaetomellic acid A (ACA), based on the copper catalysed radical cyclization (RC) of (Z)-3-(2, 2-dichloropropanoyl)-2-pentadecylidene-1, 3-thiazinane, is described. Remarkably, the process entailed:(i) a one-pot preparation of the intermediate N- α-perchloroacyl-2-(Z)-alkyliden-1, 3-thiazinanes starting from N-(3-hydroxypropyl) palmitamide,(ii) a two step smooth transformation of the RC products into ACA and (iii) ...