A series
of unprecedented tetrazole-linked imidazo[1,5-a]pyridines
are synthesized from simple and readily available
building blocks. The reaction sequence involves an azido-Ugi-deprotection
reaction followed by an acetic anhydride-mediated N-acylation–cyclization process to afford the target heterocycle.
Furthermore, the scope of the methodology was extended to diverse
R3-substitutions by employing commercial anhydrides, acid
chlorides, and acids as an acyl component. The scope for the postmodification
reactions are explored and the usefulness of the synthesis is exemplified
by an improved three-step synthesis of a guanylate cyclase stimulator.
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