| 摘要 |
<p>Title compds.(I; R1 = substituted imide, amide, imidazolydyl; R' = R, H) useful as intermidiates for cephem antibiotics were prepd by cyclization of II(R = protective group of carboxylic acid). Thus, methy1 66-phthalimidopenicillanate sulfoxide was cleaved with N-chlorosuccinimido in CCl4 to give azetidinone III, which was cyclized with SnCl4 in CH2Cl2 to give the sulfoxide of R- and S-I(R' = Me; R1 = phthalimido). Other Lewis or Broensted acids, such as, TiCl4, AlCl3, ZnBr2, SbAl5, HgCl2, ZrCl4, polyphosphoric acid, H2SO4, methan sulfuric acid and F3CCO2H, were also used.</p> |
