127680-54-0
(1S,3R,5R,6R)-8-aza-3-[1-(S)-benzyloxyethyl]-5-methyl-2,4-dioxa-bicyclo[4.2.0]octan-7-one
→
127759-32-4
(3R,4S)-4-acetoxy-3-[(R)-1-formyloxyethyl]-2-azetidinone