| abstract |
The invention relates to a method for producing 1,4-diphenyl azetidinone derivatives from suitably protected beta -substituted amino amides, in the presence of silylation agents. Said method uses cyclization catalysts that comprise phosphonium ions as the cation of formula (XII), and ions of the following general formulas (a), (b), (c) or (d) as the anion. In said formulas, the symbols, substituents and indices are defined as follows: Z = C=O, C=S, S=O, SO2 or C=NR<20>; K = O, S, NR<21> or CR<22>R<23>; L = NR<24> or CR<25>R<26>; n = 0 or 1; M = O, C=O, NR<27> or CR<28>R<29>; Q = O, S, NR<30>, CR<31>R<32>,< >C=O, C=S, S=O, SO2 or C=NR<34>; R = CR<35> or N; T = CR<36> or N; U = CR<37> or N; V = CR<38> or N; the groups R<16 >to R<19 >can represent, for example, aryl or (C1-C15) alkyl, aryl(C1-C10)alkene, and the groups R<20 >to R<32 >and R<34 >to R<38 >can represent in addition H or heteroaryl; R<39 >and R<40 >represent, for example (C1-C6) alkyl. The anion can also be R<41>O<->,< >R<42>COO<-> or Cl<->, Br<-> or I<-> (combined with Ag2O). |