| 摘要 |
<p>5R-2-(substituted methyl)penem-3-carboxylates are prepared from corresponding penicillanic acid S-oxide esters by a multistep process proceeding through a 3-methylenecepham 1-oxide ester and certain novel azetidinones of formulae <IMAGE> wherein W = SR<4> (R<4> = alkyl, aryl or heterocyclyl), <IMAGE> (R<5>, R<6> independently = alkyl, aryl, heterocyclyl), phthalimido, succimimido, SO2R<4>;R<1> = organic group; W = SR<4> if R<1> = amino or substituted amino; R<12> = carboxylate protecting group; Y = a large range of substituents.</p> |
