An alternative approach to the synthesis of anticancer molecule spirobrassinin and its 2′-amino analogues

A convenient synthesis of the cruciferous phytoalexin ( S )-(−)-spirobrassinin and its (±)-2′-amino analogues have been achieved. Our synthetic route towards ( S )-(−)-spirobrassinin is based on the CrO 3 -mediated cyclization of chiral 1-(2′,3′,4′,6′-tetra- O -acetyl- ß -D-glucopyranosyl)brassinin and subsequent removal of the chiral auxiliary. (±)-2′-Amino analogues of spirobrassinin and 1-methoxyspirobrassinin were obtained from thioureas in one step in an efficient manner with the aid of CrO 3 . New synthesized compounds were screened in vitro for antiproliferative/cytotoxic activity against six human cancer cell lines by MTT assay. Amino analogues with CF 3 functionality displayed good antiproliferative effect. Graphic abstract