The design and synthesis of the novel monocyclic enediyne-sulfide systems and their chemical and DNA cleavage properties are described. The parent enediyne-sulfide 6 possessing a hydroxy group at the allylic position was effectively synthesized via the cross-coupling of the cis-vinyl iodide 11 and the acetylene derivative 12 using a Pd(O)-Cu(I) catalyst and the cyclization reaction of the acyclic dibromide 20 employing sodium sulfide as the key steps. In addition, the esterifications of 6 using appropriate procedures provided a series of its simple derivatives 21-29 and the hybrids 38-44 containing naturally occurring intercalators, all of which are quite stable when handled at ambient temperature. The representative enediyne-sulfide 22 was smoothly aromatized by 1,8-diazabicyclo[5.4.0]undec-7-ene in cyclohexa-1,4-diene through radical pathways and by a hydroxy anion in dimethyl sulfoxide-Tris-HCl, pH 8.5 buffer through a polar pathway. Furthermore, it was clearly found that all enediyne-sulfides cleaved DNA under alkaline conditions without any additive and the hybrids 38 and 44, each of which has the aromatic moiety of the neocarzinostatin chromophore and manzamins, respectively, exhibited the strongest DNA cleaving abilities with the identical high purine base (G > A) selectivity.