Dipropylamine → Diethyl (dipropylamino)propanedioate

Dipropylamine (22.3 g, 0.22 mol) was added to a stirred solution of diethyl bromomalonate (47.8 g, 0.20 mol) in THF (400 mL) and the solution was stirred for 18 hours at room temperature. The precipitate of dipropylamine hydrobromide was filtered off and washed with THF. The THF phase was evaporated and the residual oil was partitioned between ethyl acetate (200 mL) and sodium hydroxide solution (10 mL of 4 N). The ethyl acetate phase was separated, washed with water (2×10 mL), and the solvent was removed under reduced pressure. The residual oil was dissolved in an equal volume of hexane and was applied to a silica gel column (420 g) which was eluted initially with ethyl acetate:hexane (1:20). The concentration of ethyl acetate in the eluant was increased slowly until all the diethyl (dipropylamino)malonate was eluted from the column. Fractions containing the compound as determined by TLC and GC were pooled and the solvent was removed to give diethyl (dipropylamino)malonate as an oil in 80-90% yield.

1. filtrationThe precipitate of dipropylamine hydrobromide was filtered off
2. washwashed with THF
3. customThe THF phase was evaporated
4. customthe residual oil was partitioned between ethyl acetate (200 mL) and sodium hydroxide solution (10 mL of 4 N)
5. customThe ethyl acetate phase was separated
6. washwashed with water (2×10 mL)
7. customthe solvent was removed under reduced pressure
8. dissolutionThe residual oil was dissolved in an equal volume of hexane
9. washwas eluted initially with ethyl acetate:hexane (1:20)
10. temperatureThe concentration of ethyl acetate in the eluant was increased slowly until all the diethyl (dipropylamino)malonate
11. washwas eluted from the column
12. additionFractions containing the compound
13. customthe solvent was removed

ORD record

ord-3e1f99c3d41a40d3883fd81e3052c4b1

Source dataset

uspto-grants-1993_12

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US05273975