Pyrrolotriazine-5-carboxylate ester inhibitors of EGFR and HER2 protein tyrosine kinases and a novel one-pot synthesis of C-4 subsitituted pyrrole-2,3-dicarboxylate diesters

Pyrrolotriazines with an ester group at C-5 were prepared and evaluated as inhibitors of the EGFR and HER2 receptor tyrosine kinases, validated targets for cancer therapy. The C-5 ester (15) was at least as potent as its C-6 ester analogue (17), an example of a known series of pyrrolotriazine EGRF/HER2 kinase inhibitors that show good biochemical and cellular activity. The C-5 esters were synthesized from pyrrole 2,3-diesters that were made by a new, one-pot procedure. This involved reaction of readily available N-tosyl derivatives of α-amino acid esters or ketones with triphenylphosphine and diethyl acetylenedicarboxylate to form 3-pyrrolines via an intramolecular Wittig olefination. The 3-pyrroline intermediates were not isolated but treated directly with base to eliminate toluenesulfinic acid and generate the pyrrole 2,3-diesters in good yield.