Synthesis of Benzothiazolopyrimidine Diastereomers Through a Copper‐Catalyzed Azide–Alkyne Cycloaddition/Ring‐Cleavage/[4 + 2] Cycloaddition Sequence

Copper‐catalyzed reactions of 2‐benzothiazolimines, terminal ynones, and sulfonyl azides afforded benzothiazolopyrimidine diastereomers. The transformation involved a tandem CuAAC/ring‐cleavage/[4 + 2] cycloaddition procedure with one‐pot synthesis under mild conditions. The benzothiazolopyrimidine diastereomers could be isolated, and their structure is confirmed by X‐ray single‐crystal diffraction.