(3R,4R,5S)-4-amino-5-(tert-butoxycarbonylamino)-1-cyano-3-(1-ethylpropoxy)cyclohexene

(3R,4R,5S)-4,5-bis(tert-butoxycarbonylamino)-1-cyano-3-(1-ethylpropoxy)cyclohexene

ethyl (3R,4S,5R)-5-N-formylamino-3-(1-ethylpropoxy)-4-hydroxy-1-cyclohexene-1-carboxylate

ethyl (3R,4S,5R)-5-amino-3-(1-ethylpropoxy)-4-methanesulfonyloxy-1-cyclohexene-1-carboxylate

ethyl (3R,4S,5R)-3-(1-ethylpropoxy)-5-N-formylamino-4-methanesulfonyloxy-1-cyclohexene-1-carboxylate