An Efficient,PIFA Mediated Approach to Benzo-,Naphtho-,and Heterocycle-Fused Pyrrolo[2,l-c][l,4]diazepines.An Advantageous Access to the Antitumor Antibiotic DC-81

摘要

The synthesis of a series of optically pure benzo-.naphtho-.and heterocycle-fused pyrrolo[2.1-c]-[l,4]-dia2epin-5,ll-dione derivatives starting from L-proline methyl ester is presented.The synthetic plan includes an aroylation step at the prolinc nitrogen followed by transformation of the ester residue into a N-methoxyamide group.The subsequent key cyclization step embraces the PIFA mediated formation of a N-acylnitreniurn intermediate and its succeeding intramolecular trapping by the aromatic ring.The presented general approach solves the need of starting from not very accessible amino (or a related functionality) aromatic starting materials,and its effectiveness is demonstrated in the synthesis of the antitumor antibiotic DC-81.