Preparation of Useful Buiding-Blocks for the Synthesis of 7-Azanorbornylprostanoids

The Diels-Alder adduct 4 of an N-protected pyrrole with dimethyl acetylenedicarboxylate can be transformed to 5 and 6 by short sequences which differenciate the two ester groups; these compounds are interesting starting materials for the synthesis of potential thromboxane A2 antagonists as well as other bio-active compounds.