tert-Butanol → Carbamic acid, N-(2,2-dimethyl-3-oxocyclobutyl)-, 1,1-dimethylethyl ester

Participants

Reaction Conditions

Reaction Steps

To a solution of 2,2-dimethyl-3-oxocyclobutanecarboxylic acid (1.0 equiv.) and triethylamine (1.5 equiv.) in toluene (0.2 M) was added diphenylphosphoryl azide (2.0 equiv.) slowly under ice-water bath. Then the mixture was stirred at 100° C. for 4 h. The reaction mixture was cooled down to room temperature, and tert-butanol (2.2 equiv.) was added. The resulting mixture was refluxed for 15 h. After the mixture cooled down, an aqueous solution of sodium bicarbonate and ethyl acetate were added. The organic layer was separated and the aqueous solution was extracted with ethyl acetate. The combined organic layer was washed with aqueous solution of sodium bicarbonate and brine, dried over anhydrous sodium sulfate and filtered. The filtrate was concentrated under vacuum, the residue was purified by silica gel column chromatography (7% ethyl acetate in petroleum ether) to afford the title product (16% yield). 1H NMR (300 MHz, CDCl3) δ (ppm) 4.81-4.70 (m, 1H), 4.05-3.93 (m, 1H), 3.37 (dd, J1=18.0 Hz, J2=9.0 Hz, 1H), 2.89 (dd, J1=18.0 Hz, J2=6.9 Hz, 1H), 1.48 (s, 9H), 1.28 (s, 3H), 1.13 (s, 3H).

Provenance & Evidence