Table 2. Optimization of the reaction conditions for construction of C–N axially chiral pyrazoles^a.

Entrya	hv (nm)	Base	Yieldb (%)	erc
1d	—	—	43	70 : 30
2	420	—	55	70 : 30
3	420	K2CO3 (0.8 equiv.)	84	92 : 8
4e	420	Cs2CO3 (1.0 equiv.)	80	95 : 5

^aUnless otherwise noted, all oxidations were performed with E2, base (1.0 equiv.), DDQ (1.5 equiv.) in toluene (0.1 M) under an air atmosphere at 20 °C and under 5 W LED irradiation.

^bThe overall isolated yield of the two steps.

^cDetermined by HPLC analysis on a chiral stationary phase.

^dAt 60 °C.

^eAt −20 °C.