Table 1.

Synthesis of deuteropyrazolo[1,5-a]pyridine derivatives^a.

Product and D content (%)b	Yield (%)	Product and D content (%)b	Yield (%)
3	70	5	34c
6	87	7	19d
8, 9	63

^aH/D-exchange: salt 1a–c (0.20 mmol), K₂CO₃ (1.0 mmol), D₂O (1.5 mL), 80 °C, 5 min; 1,3-cycloaddition: acetylene compound (0.2 mmol), MeCN (5 mL), chloranil (0.15 mmol), rt, 1 h. ^bD content (%) was determined by ¹H NMR. ^cDD and yield after two runs in D₂O. ^dDD and yield after H/D exchange for 1 h in D₂O at 80 °C.