tert-Butyl 2,2,2-trichloroacetimidate

Chemical Properties

Clear colorless to pale yellow liquid

Application

Tert-Butyl 2,2,2-trichloroacetimidate can be used as a reagent for the preparation of tert-butyl esters, tert-butyl ethers and tert-butyl amines.

Uses

tert-Butyl 2,2,2-trichloroacetimidate is used to produce di-tert-butyl peroxide at temperature of -5°C. It may be used in the synthesis of N-α-Fmoc-phospho(1-nitrophenylethyl-2-cyanoethyl)-L-serine, caged building block. It may be used in the conversion of alcohols and carboxylic acids to their respective ethers and esters.

Preparation

Potassium t-Butoxide (1.68 g, 15 mmol) was dissolved in t-butanol (30 mL) and  this solution was added over 15 min to a stirred solution of Trichloroacetonitrile (21.6 g, 15 mL, 15 mmol) in dry diethyl ether (30 mL) cooled to 0 °C under nitrogen. The yellow mixture was allowed to warm to 20 °C over 1 h, and then heated to reflux for 1 h. After the reaction mixture had been cooled to rt, volatiles were removed on the rotary evaporator and the residual oil was dissolved in pentane (30 mL). The solution was filtered and the pentane was removed on the rotary evaporator. The residue was then distilled to yield 23 g (70%), bp 65-69 °C/12 mmHg, which solidified on storage.

Synthesis

Tert-butyl trichloroacetimidate (TBTA) was synthesized as follows: 69 ml (0.069 mol) of potassium tert-butanolate (1 M in tert-butanol) was dissolved in 69 ml of diethyl ether. The above solution was slowly added dropwise to 69 ml of ether solution containing 100 g (0.69 mol) of trichloroacetonitrile over a period of 30 min at 0 °C. After the dropwise addition was completed, the reaction mixture was gradually warmed to room temperature over a period of 1 hour, followed by continued stirring under reflux conditions for 1 hour. Upon completion of the reaction, the mixture was cooled to room temperature and the solvent was removed by evaporation under reduced pressure to give an oily product. The oily product was dissolved in 140 mL of hexane and filtered to remove the insoluble potassium salt. The filtrate was concentrated by reduced pressure evaporation and the residue was vacuum distilled. The fraction distilled at 2.4 mmHg and 40 °C was collected to give 105 g of tert-butyl trichloroacetimidate in 69% yield (as TCA). The structure of the product was confirmed by nuclear magnetic resonance hydrogen (1H NMR, 300 MHz, CDCl3) and carbon (13C NMR, 75.45 MHz, CDCl3) spectra with the following data: 1H NMR δ 1.58 (s, 9H), 8.21 (br, s, 1H); 13C NMR δ 27.23, 83.86, 92.78, 160.33 . (Ref: Armstrong et al.)

References

[1] Patent: WO2007/106546, 2007, A2. Location in patent: Page/Page column 12