Dicyclohexylcarbodiimide → 2-(3,3,5,5-Tetramethyl-1-vinylcyclohexyl)acetamide

Participants

Reaction Steps

N-Hydroxysuccinimide (0.25 g, 2.2 mmol) and N,N′-dicyclohexyl carbodiimide (0.45, 2.2 mmol) was added to a solution of cyclohexylacetic acid 17 (0.45 g, 2 mmol) in THF (5 ml). The mixture was stirred for 18 h at room temperature and cooled in an ice bath. 25% aqueous NH4OH (2 ml) was added in one portion and the mixture was stirred at room temperature for 2 h. The precipitate was filtered off and washed with diethyl ether (30 ml). The organic phase of filtrate was separated and washed with 5% aqueous KHSO4 (10 ml) and brine. The extract was dried over MgSO4, filtered and evaporated. The residue was purified by flash chromatography on silica gel (light petroleum ether-ethyl acetate, 4:1 to 1:1) to give 18 (0.34 g, 76%) as a colorless solid with m.p. 44-46° C. 1H-NMR (CDCl3, TMS): 0.91 (6H, s, 3,5-CH3); 1.02 (6H, s, 3,5-CH3); 1.00-1.30 (4H, m, 4-CH2 and 2,6-CH); 1.85 (2H, d, 14 Hz, 2,6-CH); 2.13 (2H, s, CH2C═O); 5.18 and 5.19 (total 2H, both d, 18 and 11 Hz, ═CH2); 5.40 and 5.60 (total 2H, both br s, NH2) and 6.03 ppm (1H, dd, 18 and 11 Hz, ═CH).

Provenance & Evidence