The designed hybrids 5–11 containing the DNAcleavableenediyne 4 and naturally occurring DNAintercalators 12–18cleave DNA effectively under alkaline conditions without any additive; the hybrids 5 and 11 exhibit the strongest DNA-cleaving abilities with the identical high purine base (G>A) selectivities for their DNA-cleavage profiles.
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.
Design and synthesis of 1-thia-3,8-diyn-5-ene systems with DNA-cleaving properties related to the neocarzinostatin chromophore
1-Thia-3,8-diyn-5-ene compounds 5–10, which are derivatives of the parent compound 1 are synthesized in a short step with high stability; these compounds show DNA-cleaving activity under basic conditions in the absence of any additives.
The novel enyne-allene sulfones 5–8 were prepared by m-chloroperbenzoic acid oxidation of the corresponding enediyne sulfides 1–4; the enyne-allene sulfones 6–8 having a leaving group at the allylic position were aromatized by 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU)viathe allene-ene-cumulene intermediate 10 and showed DNA-cleaving activities under basic conditions without any additive.