Penems: synthesis and antibacterial activity of 2-(1-azolyl) derivatives.

thesis by Woodward1},many research groups have prepared variously substituted penems, including derivatives bearing hetero-substituents at C-2. Whereas the vast majority of these have been sulfur derivatives2~6), analogous to the naturally occurring thienamycin and a few 2oxy-substituted penems have been synthesized70 , no nitrogen derivatives have yetf been described. In continuation of our studies in the 2-(heterocyclyl)alkyl series8>9) , we decided to concentrate on penems 1 and 2, featuring an azole heterocycle directly linked to the penem nucleus through a ring nitrogen (Scheme 1). In contrast to their unreactive dialkylamino homologuesn, the azolyl-dithiocarbamates 7 proved to be good substrates for the Wittig ring closure. Depending on the nature of the