Tris(2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']-bis(1,3)dioxole-4-yl)methane (1.35 g, 2.0 mmol (Example 17)) was dissolved in dry THF (400 mL) under N2, and the temp was lowered to -40° C. and n-BuLi (4.86 mL, 12.2 mmol) was added and the temperature was allowed to rise gradually to 0° C. The mixture was cooled to -60° C., and a solution of ethylchloroformate (4.0, 36.7 mmol) in THF (50 mL) was added. The reaction mixture was left overnight and worked up as described under Example 20 above. The chromatography gave (0.41 g, 24%) of tris(8-ethoxycarbonyl-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']-bis(1,3)dioxole-4-yl)methane.
