We have previously reported a novel series of oxalyl-aryl-amino benzoic acid-based, catalytic site-directed, competitive, reversible protein tyrosine phosphatase 1B (PTP1B) inhibitors. With readily access to key intermediates, we utilized a solution phase parallel synthesis approach and rapidly identified a highly potent PTP1B inhibitor (19, Ki=76 nM) with moderate selectivity (5-fold) over T-cell PTPase (TCPTP) through interacting with a second phosphotyrosine binding site (site 2) in the close proximity to the catalytic site.