Imidazo[1,5-
a]pyrazines
1 undergo regioselective C3-metalation and C5/C3-dimetalation to afford a range of functionalized derivatives
2a−
2g (Table
1), and
4a−
4d (Table
2). Under similar conditions, the C3-methyl derivatives
2a and
5 undergo surprising regioselective C5-deprotonation to afford, after electrophile quench, products 4b and
6a−
6p (Table
3), results that are rationalized by quantum mechanical calculations. Benzamide
7b, obtained from such metalation chemistry followed by Suzuki cross coupling, undergoes directed remote metalation-cyclization to afford
8, representing the hitherto unknown triazadibenzo[
cd,
f]azulen-7(6
H)-one tricyclic ring system.