Discovery of morpholine-based aryl sulfonamides as Na v 1.7 inhibitors.

Replacement of the piperidine ring in the lead benzenesulfonamide Nav1.7 inhibitor 1 with a weakly basic morpholine core resulted in a significant reduction in Nav1.7 inhibitory activity, but the activity was restored by shortening the linkage from methyleneoxy to oxygen. These efforts led to a series of morpholine-based aryl sulfonamides as isoform-selective Nav1.7 inhibitors. This report describes the synthesis and SAR of these analogs.