From (E)- and (Z)-ketoximes to N-sulfenylimines, ketimines or ketones at will. Application to erythromycin derivatives

Reactions of (E)- and (Z)-ketoximes with trialkylphosphines and diphenyl disulfide (PhSSPh) have been compared to gain insight into the mechanisms involved and their potential applications. N-Sulfenylimine isomers and ketimines have been spectroscopically characterised. Both the E and Z isomers of erythromycin A oxime, when treated with Bu3P and PhSSPh (1:4:8 ratio), give the same N-phenylsulfenyl ketimine (of configuration E) as the major compound, whereas with Bu3P or Me3P and PySeSePy (1:8:4 ratio) afford the imine in good yield. Clarithromycin oxime behaves similarly.