Acetone → Diethyl isopropylidenemalonate

Participants

Reaction Conditions

Reaction Steps

Diethyl isopropylidenemalonate was prepared according to the procedure of E. L. Eliel, R. O. Hutchins, and Sr. M. Knoeber, Organic Synthesis Coll. Vol. VI, 442, 1988, with following modifications. A mixture of acetone (54 g, 0.93 mol, Mallinckrodt), diethyl malonate (100 g, 0.62 mol, Aldrich), acetic anhydride (80 g, 0.78 mol, Mallinckrodt), and zinc chloride (12.5 g, 0.78 mol, Aldrich) was refluxed (90° C. oil bath) for 18 h while protected from moisture. The reaction solution was diluted with dichloromethane (500 ml) and washed with cold water (3×50 ml). The aqueous washes were combined and extracted with dichloromethane. All dichloromethane layers were combined and concentrated by spin evaporation in vacuo. The residual oil was distilled under vacuum and the fractions boiling at 102°-138° C. at 12 Torr were combined with the pot residue and heated for 6 h with a 200° C. oil bath. The dark oil was redistilled to give 40.1 g (32%) of diethyl isopropylidenemalonate as a clear oil: b.p., 110°-115° C./12 mm Hg: NMR (DMSO-d6): d 4.19 (q, 4 H, J=7.2 Hz, OCH2), 2.03 (s, 6 H, =C(CH3)2), 2.25 (t, 6 H, J=7.2 Hz, CH2).

Provenance & Evidence