Sodium Carbonate → 9-Dicyclopropylmethyl-8-ethyl-6-(6-methyl-2,3-dihydrobenzofuran-5-yl)purine

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Reaction Steps

Part G. A mixture of the boronic acid from Part F (298 mg, 1.67 mmol), 6-chloro-9-dicyclopropylmethyl-8-ethylpurine (309 mg, 1.12 mmol), 2 N aqueous sodium carbonate solution (1.7 mL, 3.4 mmol) and triphenylphosphine (61 mg, 0.233 mmol) in DME (20 mL) was degassed by repeated cycles of brief vacuum pumping followed by nitrogen purging. To this was added palladium(II) acetate (13 mg, 0.058 mmol), and the mixture was degassed again and then heated to reflux for 14 hours. It was cooled, and poured into water (100 mL). This mixture was extracted with ethyl acetate (2×100 mL), and the extracts were washed in sequence with brine (60 mL), combined, dried over sodium sulfate, filtered and evaporated. The residual material was separated by column chromatography (silica gel, 20:80 ethyl acetate-hexane) to afford the title product as a solid. This was recrystallized to purity from ether (253 mg, 0.77 mmol, 69%). m.p. 147-148° C. TLC RF 0.18 (30:70 ethyl acetate-hexane). 1H NMR (300 MHz, CDCl3): d 8.88 (1H, s), 7.60 (1H, s), 6.77 (1H, s), 4.61 (2H, t, J=8.6 Hz), 3.44 (1H, v br), 3.24 (2H, t, J=8.6 Hz), 2.94 (2H, br), 2.44 (3H, s), 2.03 (2H, v br), 1.45 (3H, br t, J=6 Hz), 0.89-0.79 (2H, m), 0.58 (2H, br), 0.50-0.40 (2H, m), 0.27-0.17 (2H, m). MS (NH3-CI): m/e 377 (4), 376 (27), 375 (100). Analysis calc'd for C23H26N4O: C, 73.77; H, 7.01; N, 14.96; found: C, 73.69; H, 7.08; N, 14.40.

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