A mixture of Intermediate K (1.32 g, 4.0 mmol), 4-isobutoxyphenylboronic acid (1.94 g, 10.0 mmol), tetrakis(triphenylphosphine)palladium(0) (1.00 g, 0.86 mmol), solution of sodium carbonate (2.12 g, 20 mmol) in water (15 mL), butanol (50 mL), and toluene (30 mL) was vigorously stirred and heated under argon at 100° C. for 16 hours. The reaction mixture was poured into water (300 mL), stirred for 30 minutes and extracted with toluene/ethyl acetate/hexane (5:3:2, 500 mL). The volatiles were removed under reduced pressure, and the residue was chromatographed (silica gel, hexane/dichloromethane, 1:1). The separated product was recrystallized from ethanol to give pure 4,7-bis(4-isobutoxyphenyl)-2-isobutyl-2H-benzo[d][1,2,3]triazole, Compound 42 (1.57 g, 83% yield). 1H NMR (400 MHz, CDCl3): δ 7.99 (d, J=8.7 Hz, 4H, 4-i-BuOC6H4), 7.55 (s, 2H, benzotriazole), 7.04 (d, J=8.8 Hz, 4H, 4-i-BuOC6H4), 4.58 (d, J=7.3 Hz, 2H, i-Bu), 3.79 (d, J=6.6 Hz, 4H, 4-i-BuOC6H4), 2.59 (m, 1H, i-Bu), 2.13 (m, 2H, 4-i-BuOC6H4), 1.04 (d, J=6.6 Hz, 12H, 4-i-BuOC6H4), 1.00 (d, J=6.6 Hz, 6H, i-Bu). UV-vis spectrum (PVB): λmax=359 nm. Fluorimetry (PVB): λmax=434 nm.
