458. 1,2,3-Benzothiadiazole. Part I. Nitro-, amino-, and hydroxy-derivatives

Abstract

4-and 6-Nitro-lJ2,3-benzothiadiazoles are prepared from the corresponding nitrobenzothiazoles by ring opening, followed by tetrazotisation (and decomposition) of the derived diaminodiphenyl disulphide, thus providing a convenient route to 4-and 6-derivatives of 1,2,3-benzothiadiazole. The method fails with 5-and 7-nitrobenzothiazole.By Fries and Reitz's method 1,2,3-benzothiadiazole yields 5-and 7-mononitro-derivatives, and not 4-and 7-isomers as previously believed.The four nitrobenzothiadiazoles are orientated for the first time, by relating elution behaviour to dipole moments. The structures of the aminobenzothiadiazoles follow .Diazotised 6-amino-1,2,3-benzothiadiazole yields the corresponding 6-hydroxy-compound but similar decompositions of the diazotised 4-and 7-amino-derivatives gave azo-dyes. THE only significant method for preparing 1,2 ,3-benzothiadiazoles is by diazotisation of o-aminothiophenols,l and a useful route to the latter is by ring opening of benzothiazoles. We recently described a method making all four nitrobenzothiazoles readily available and have now investigated the conversion of these into the corresponding nitrobenzothiadiazoles. Boggust and Cocker described an' improved method for the ring fission, using refluxing ethanolic hydrazine hydrate and employed it to prepare di-(o-amino-5-nitrophenyl) disulphide from 6-nitrobenzothiazole. We converted this disulphide into 6-nitro-lJ2,3-benzothiadiazole by Burawoy and Turner's procedure (used to prepare the Hodgson and Dodgson, J . SOC. Dyers and Colourists, 1948, 64, 65. 3 Ward and Poesche, J., 1961, 2825. 3 Boggust and Cocker, J., 1949, 355.

Exploiting an Allosteric Binding Site of PRMT3 Yields Potent and Selective Inhibitors

“…The key intermediate 8 was prepared according to published procedures. 58 Commercially available 6-nitrobenzothiazole was first ring-opened to yield the disulfide intermediate, which was then converted to the 6-nitrobenzothiadiazole intermediate. Subsequent reduction of the nitro group afforded the intermediate 8 .…”

“…To further investigate the middle urea moiety, we designed and synthesized the urea bioisosteres and more rigid analogues outlined in Scheme . The key intermediate 8 was prepared according to published procedures . Commercially available 6-nitrobenzothiazole was first ring-opened to yield the disulfide intermediate, which was then converted to the 6-nitrobenzothiadiazole intermediate.…”