Dimethylformamide → 1,1-Bis(propan-2-yl) 3,3-dimethoxycyclobutane-1,1-dicarboxylate

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Reaction Conditions

Reaction Steps

Diisopropyl malonate (72 g, 0.38 mol) was added dropwise, under nitrogen, to a stirred suspension of sodium hydride (17 g, 0.42 mol) in dry N,N-dimethylformamide (140 mL, 1.8 mol) at a rate such that the temperature was maintained below 70° C. On cessation of hydrogen evolution, 1,3-dibromo-2,2-dimethoxypropane (50 g, 0.2 mol) was added in one portion and the mixture heated at 140° C. for 48 h. The cooled mixture was poured into sat. solution of ammonium chloride (300 mL), extracted with hexane. The organic layer was washed with sat. sodium bicarbonate, brine, dried over sodium sulfate, and evaporated to dryness. The residue was distilled under vacuum (oil pump) to afford the desired cyclobutane compound (31 g, 56.32%). bp 92-94° C./0.01 mm). 1H NMR (400 MHz, CDCl3): δ 5.02 (2H, sept., J=6.4 Hz), 3.12 (6H, s), 2.66 (4H, s), 1.11 (12H, d, J=6.4 Hz.) ppm.

Provenance & Evidence