Condensed heterocyclic systems containing N-& S-medium-sized rings, in particular, thiazepine, thiazocine, and thiazonine systems are important substructures present in a large variety of biologically active natural products. Methods for the formation of thiazonines and higher ring systems, however, remain largely unknown. The research presented addresses the synthesis and characterization of new heterocyclic skeletons incorporating N-& S-medium-sized-rings fused to quinolines to form the targeted tetracyclic 1,4-thiazocines, 1,4-thiazonines and 1,4-thiazecines by Friedel-Crafts cycliacylation and Beckmann-rearrangement sequences. The ambient conditions, short-reaction times and easy work-up procedures make this synthetic strategy a better protocol for the synthesis of medium-sized heterocyclic rings bearing nitrogen and sulphur atoms.