Acetone → Ethyl 4-(propan-2-yl)piperazine-1-carboxylate

A solution of ethyl 1-piperazinylcarboxylate (25.0 mL, 0.171 mole) and acetone (37.7 mL, 0.513 mole) in methanol (MeOH) (500 mL) was cooled to 0°-5° C. Sodium cyanoborohydride (10.7 g., 0.171 mole) was added in two portions. The so-formed mixture was stirred at 0°-5° C. for 8 hours while maintaining the pH at 4-6 by dropwise addition of 6N HCl. The temperature of the reaction mixture was allowed to slowly rise to RT overnight. The reaction mixture was evaporated in vacuo to provide a residue which was dissolved in H2CCl2 (500 mL) and 5% NaHCO3 (500 mL). The H2CCl2 layer was separated, washed with brine (500 mL), dried over anhydrous MgSO4, and evaporated in vacuo. The so-formed residue was chromatographed on silica gel, eluting with 1% MeOH/H2CCl2 (v/v) containing 1 mL of conc. NH4OH per liter of solution to give 18.9 g of the title compound of Example 67(a) as a gum, M/e, M+ 201.

1. temperaturewhile maintaining the pH at 4-6
2. waitto slowly rise to RT overnight
3. customThe reaction mixture was evaporated in vacuo
4. customto provide a residue which
5. customThe H2CCl2 layer was separated
6. washwashed with brine (500 mL)
7. dry with materialdried over anhydrous MgSO4
8. customevaporated in vacuo
9. customThe so-formed residue was chromatographed on silica gel
10. washeluting with 1% MeOH/H2CCl2 (v/v)
11. additioncontaining 1 mL of conc. NH4OH per liter of solution

ORD record

ord-08fdaff3b6ae4941b6f0f814bc9ec486

Source dataset

uspto-grants-1991_08

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US05039676