Abstract The title betain was found to display both 1, 3 and 1, 5-dipolar reactivity, depending on reaction conditions. Whereas the reaction with aromatic isothiocyanates in nonpolar solvents produced cycloadducts in concerted manner stewise addition in dimethylformamide led to a single product, presumably with sevenmembered ring. An open-chain intermediate could be isolated and characterized.
![1-(6-bromobenzo[d]thiazol-2-yl)ethanone Structure](https://image.chemsrc.com/caspic/265/94834-01-2.png)
