(3R,4S)-allyl 4-(tert-butoxycarbonylamino)-3-(tert-butyldimethylsiloxy)-5-methylhexanoate

(3R,4S)-allyl 3-(tert-butyldimethylsiloxy)-4-{(S)-2-[(S)-2-[(S,E)-3-(4- methoxybenzyloxy)-7-(tritylthio)hept-4-enoylamino]-4-(methylthio)butanoylamino]-3-tritylthio(propionylamino)}-5-methylhexanoate