Two practical syntheses of (2S, 4S)-4-tert-butoxycarbonylamino-2-methylpyrrolidine, an important intermediate for quinolone antibacterial agents, have been developed through the combination of diastereo and enantioselective reactions starting from ethyl crotonate and L- alanine, respectively.
[Davis, Franklin A.; McCauley, John P.; Chattopadhyay, Sankar; Harakal, Mark E.; Towson, James C.; et al. Journal of the American Chemical Society, 1987 , vol. 109, # 11 p. 3370 - 3377]
