First observation of Chapman rearrangement of a pseudosaccharyl ether in the solid state: the thermal isomerization of 3-(methoxy)-1,2-benzisothiazole 1,1-dioxide revisited

• Autor(a) principal: Almeida, R.
• Data de Publicação: 2008
• Outros Autores: Gómez-Zavaglia, A., Kaczor, A., Cristiano, M. L. S., Eusébio, M. E. S., Maria, T. M. R., Fausto, R.
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10316/17941; https://doi.org/10.1016/j.tet.2008.02.007
• topic: Pseudosaccharin; 3-(Methoxy)-1,2-benzisothiazole 1,1-dioxide; Chapman rearrangement; DFT calculation; Infrared spectroscopy; Thermomicroscopy

3-(Methoxy)-1,2-benzisothiazole 1,1-dioxide, a pseudosaccharyl ether, was long ago known to undergo a thermal Chapman-like [1,3′]-isomerization to the corresponding N-methyl pseudosaccharin at temperatures above its melting point (ca. 184 °C) [Hettler H., Tetrahedron Lett.1968, 15, 1793]. In the present study, it is shown that this rearrangement can also take place in the solid state, at temperatures as low as 150 °C. This was the first observation of a Chapman-like [1,3′]-isomerization in pseudosaccharyl ethers in the solid state. The study has been carried out by a multidisciplinary approach using temperature dependent infrared spectroscopy, differential scanning calorimetry (DSC), and polarized light thermomicroscopy, complemented by theoretical methods. Graphical abstract