A solution of 3,5-dichloro-4-methyl-pyridine (0.593 g, 3.66 mmoles) in tetrahydrofuran (200 mL) is cooled to −60° C. under nitrogen atmosphere. A 1M solution of lithium bis(trimethylsilyl) amide (4.4 mL, 4.4 mmoles) is added dropwise and the resulting mixture is stirred at −60° C. for 30 minutes. A solution of 4-methoxy-8-nitro-dibenzofuran-1-carbonyl chloride (3a) (0.75 g, 2.44 mmoles) in dry tetrahydrofuran (20 mL) is added dropwise, maintaining the temperature below −60° C. After stirring for 15 minutes at −60° C., the mixture is stirred at room temperature for 3.5 hours. The mixture is then quenched with a saturated NH4Cl solution (20 mL); the product precipitated as a solid which is recovered by filtration and washed with methanol to yield 340 mg of the title compound.
