Synthesis
tert-butyl cyanoacetate synthesis: 2-Cyanoacetic acid (1.701 g, 20 mmol) was suspended in a cetonitrile (20 ml) and tert-butanol (2.391 ml, 25.00 mmol). To this, a solution of N,N′-Dicyclohexylcarbodiimide (4.54 g, 22.00 mmol) in DCM (22 ml) was added under stirring at RT. The reaction mixture was stirred for 30 minutes, then filtered through Celite, and the solvents were evaporated. Proton NMR analysis of the residue showed complete conversion to the product. The product, tert-butyl cyanoacetate was not purified, but was taken straight through to the next reaction.
1H NMR (400 MHz, CDCl 3 ) δ 3.37 (s, 2H), 1.50 (s, 9H).
Purification Methods
The IR spectrum of a film should have bands at 1742 (ester CO) and 2273 (CN), but no band at ca 3500 broad (OH) cm-1 . If it does not have the last-named band, then fractionally distil; otherwise dissolve in Et2O, wash with saturated aqueous NaHCO3, dry over K2CO3, evaporate Et2O, and distil the residue under a vacuum (see tert-butyl ethyl malonate for precautions to avoid decomposition during distillation). [Beech & Piggott J Chem Soc 423 1955, Dahn & Hauth Helv Chim Acta 42 1214 1959, Beilstein 2 I 255.]
