for the following products
(3R,4S)-1-Benzoyl-4-phenyl-3-(triethylsilyloxy)azetidin-2-one | (3R,4S)-1-Benzoyl-4-phenyl-3-[(triethylsilyl)oxy]-2-azetidinone | Paclitaxel side chain no 2 and (3R,4S)-1-Benzoyl-3-[(triethylsilys)oxy]-4-phenyl-2-azetidinone
