Synthesis of Alicyclic 2-Methylenethiazolo[2,3- b ]quinazolinone Derivatives via Base-Promoted Cascade Reactions.

The synthesis of alicyclic 2-methylenethiazolo[2,3- b ]quinazo-l-inones is performed via base-promoted cascade reactions, starting from either alicyclic β-amino propargylamides using carbon disulfide, or from alicyclic ethyl 2-isothiocyanatocarboxylates by addition of propargylamine. In both cases the cascade reaction proceeds by way of a favoured 5 - exo -dig process during the second ring closure, as confirmed by full NMR spectroscopic assignments. Moreover, a high-yielding retro--Diels–Alder (RDA) reaction is performed on the norbornene derivatives leading to 2-methylene-2 H -thiazolo[3,2- a ]pyrimidin-5(3 H)-ones. The obtained compounds exert modest antiproliferative activities against a panel of human gynaecological cancer cell lines. [ABSTRACT FROM AUTHOR]