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

HRID 1692911Notes

Reaction equation

[C:1]([O:10][CH:11]([CH3:13])[CH3:12])(=[O:9])[CH2:2][C:3]([O:5][CH:6]([CH3:8])[CH3:7])=[O:4].[H-].[Na+].CN(C)C=O.[H][H].Br[CH2:24][C:25]([O:30][CH3:31])([O:28][CH3:29])[CH2:26]Br>[Cl-].[NH4+]>[CH3:29][O:28][C:25]1([O:30][CH3:31])[CH2:26][C:2]([C:3]([O:5][CH:6]([CH3:7])[CH3:8])=[O:4])([C:1]([O:10][CH:11]([CH3:13])[CH3:12])=[O:9])[CH2:24]1

Participants

Conditions

Temperature: 140 °C

Procedure

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.

Workup

temperaturewas maintained below 70° C
extractionextracted with hexane
washThe organic layer was washed with sat. sodium bicarbonate, brine
dry with materialdried over sodium sulfate
customevaporated to dryness
distillationThe residue was distilled under vacuum (oil pump)

Sources & evidence

ORD record: ord-6adfcbcc007245c59346dc9511aa5941
Source dataset: uspto-grants-2012_04
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US08158616B2

Reaction notes

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