tert-Butyl 2-(3-methoxycarbonyladamant-1-ylcarbonylamino)pent-4-ynoate (0.44 g) was dissolved in 0.8 mL of dry benzene under nitrogen. To this solution was added a catalytic amount of CuSO4 and the reaction mixture was brought to reflux. N,N-Dimethyl acetoacetamide was added dropwise in excess. Evolution of nitrogen was observed. The addition was complete after 30 min. The reaction was then heated for another 30 min. After cooling the reaction mixture, the solvent was evaporated under reduced pressure and the crude product was purified on a prep plate (silica gel; EtOAc/hexanes, 2:3) to afford the title compound as an oil.
