Sixteen new isothiazoloisoxazole 1,1-dioxides, one new isothiazolotriazole and one new isothiazolopyrazole have been synthesised by using 1,3-dipolar cycloadditions to isothiazole 1,1-dioxides. One sub-set of these isothiazoloisoxazoles showed low μM activity against a human breast carcinoma cell line, whilst a second sub-set plus the isothiazolotriazole demonstrated an interesting restricted rotation of sterically hindered bridgehead substituents. A thiazete 1,1-dioxide produced from one of the isothiazole 1,1-dioxides underwent conversion into an unknown 1,2,3-oxathiazolin-2-oxide upon treatment with Lewis acids, but was inert towards 1,3-dipoles and cyclopropenones. Six supporting crystal structures are included.
Blackburn, J., Molyneux, G., Pitard, A., Rice, C. R., Page, M. I., Afshinjavid, S., ... Hemming, K. (2016). Synthesis, conformation and antiproliferative activity of isothiazoloisoxazole 1,1-dioxides. Organic and Biomolecular Chemistry, 14(6), 2134-2144. https://doi.org/10.1039/C5OB02586A