| abstract |
The present invention relates to novel processes for the preparation of 3-methylenecephams. More specifically, the present invention relates to the intramolecular cyclization of penicillin sulfoxide derived monocyclic azetidinone derivatives with organometallic catalysts of the formula III. n n n ME x (H 2 O) y (III) n n n wherein: n M is Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Zr, Hf, Th, Nb, Ta, U, Bi, or In; n E is O[SO 2 (C 1 -C 6 polyfluoroalkyl)], N[SO 2 (C 1 -C 6 polyfluoroalkyl)] 2 , or C[SO 2 (C 1 -C 6 polyfluoroalkyl)] 3 ; n x is 3; n y is 0, 1, 2, 3, 4, 5, 6, 7, 8, or 9. |