A 1.6 M solution of n-butyllithium in hexane (5.7 ml, 9.1 mmol) was added within 10 min to a −78° C. cold solution of N,N′-diisopropylethylamine (1.55 ml, 9.1 mmol) in THF (25.5 ml). The solution was stirred for 10 min at 5° C. and cooled again to −78° C. A solution of 2-(4-chloro-phenyl)-2H-indazole (1.7 g, 7.4 mmol; Liu, Rui; Zhu, Yong-ming; Qin, Lie-na; Ji, Shun-jun; Katayama, Haji. Heterocycles (2007), 71(8), 1755-1763.) in THF (8.5 ml) was added, the suspension was stirred for 15 min at 0° C., cooled to −78° C. and cyclohexane-carbaldehyde (1.1 ml, 9.1 mmol; CAS Reg. No. 2043-61-0) was added. The reaction mixture was stirred at ambient temperature for 14 h. Under ice cooling saturated aqueous ammonium chloride solution was added and the mixture was extracted two times with iPrOAc. The combined extracts were washed with ice water/brine 1/1 and dried over Na2SO4. After filtration the solvent was removed under reduced pressure and the residue was purified by column chromatography (silica gel, iPrOAc/heptane) to give the title compound (1.1 g, 3.2 mmol; 43%) as yellow foam. MS: m/e=341.2 [M+H+].
