Dicyclohexylcarbodiimide → Bis(1,1-Dimethylethyl) 2-[(2,2-dimethyl-4,6-dioxo-1,3-dioxan-5-ylidene)(hydroxy)methyl]-1,4-piperazinedicarboxylate

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Reaction Steps

To a solution of 1,4-bis{[(1,1-dimethylethyl)oxy]carbonyl}-2-piperazinecarboxylic acid (may be prepared as described in Intermediate 1; 14.58 g) in dichloromethane (500 mL) was added DMAP (8.09 g) and then DCC (13.66 g). The reaction was stirred for 15 minutes and then 2,2-dimethyl-1,3-dioxane-4,6-dione (9.54 g) (Meldrum's acid) was added. The reaction was stirred at room temperature for 20 h. A solid was present, which was filtered off and the product was found to be in the filtrate. The filtrate was washed with water (2×200 mL) and brine (200 mL) before it was dried (Na2SC4), filtered and the solvent removed under vacuum. The crude material was then redissolved in DCM (500 mL) and 50 mL removed and this was washed with 1M HCl (2×20 mL) before the organic phase was dried (Na2SC4), filtered and the solvent removed under vacuum to give the title compound (1.16 g). This process removed the DMAP impurity. The process was repeated with the remaining DCM solution, washing with 1M HCl (2×300 mL) before the solution was dried (Na2SC4), filtered and the solvent removed under vacuum to give the title compound as yellow viscous oil (16.65 g).

Provenance & Evidence