Synthesis, structure and cytotoxicity of trimethylsilyl oligothienylcarbaldehydes and their derivatives

Trimethylsilyl end-capped bi- and terthiophene carbaldehydes were prepared by reaction of bi- and terthienyl lithium with DMF. Condensation of 5-trimethylsilyl-2,2′-bithiophene-5′-carbaldehyde with dinitrile of malonic acid gave silylbithienyl methylidenedinitrile in good yield, while reaction with hydroxylamine was accompanied by desilylation. The reaction of hydroxylamine with silylbithienyldinitrile leads to the formation of 2-[5-(5′-trimethylsilyl-2,2′-bithienyl)methylidene]malonic acid bisamidoxime. The cytotoxic effect of bi- and terthiophene derivatives was investigated in vitro on two monolayer tumor cell lines: MG-22A (mouse hepatoma) and HT-1080 (human fibrosarcoma). The molecular structure of 5-trimethylsilyl-2,2′-bithiophene-5′-carbaldehyde was studied by X-ray diffraction.