Expedited Route to Fully Substituted Amino-Pyrazole Building Blocks and Their Further Transformations

We report here an efficient and easily
reproducible two-step approach
to heterocycle-substituted amino-pyrazoles from heterocyclic acetonitriles
and their unprecedented subsequent transformations to fully substituted
pyrazoles. Such transformations include regioselective derivatization
from polyamino derivatives, formation of tetracyclic compounds in
up to 45% overall yield, and deaminative transformations through diazotization,
followed by arylation through Suzuki–Miyaura cross-coupling
and C–H activation, providing arylated pyrazoles in up to 71%
yield over four steps. This strategy allows the swift introduction
of significant molecular complexity to a range of scaffolds.