4-nitrobenzyl (4R,5S,6S)-3-[(diphenylphosphono)oxy]-6-[(R)-1-hydroxyethyl]-4-methyl-7-oxo-1-azabicyclo[3.2.0]hept-2-ene-2-carboxylate   、                                                                                      
1-(N,N-dimethyl-aminosulfonyl)-3-mercapto-azetidine                                                                                                                                                                                                                                                                                                          以to give 14.1 g of the product with a yield of 52.1%的产率得到p-nitrobenzyl (4R,5S,6S)-3-[1-(N,N-dimethylaminosulfonyl)-azetidin-3-yl]thio-6-[(1R)-1-hydroxyethyl]-4-methyl-7-oxo-1-aza-bicyclo[ 3.2.0]hept-2-ene-2-carboxylate