Modifications to the previously reported spiroindenylpiperidine camphorsulfonamide oxytocin (OT) antagonist L-366,509 have produced a new series of o-tolylpiperazine (TP) camphorsulfonamides. A number of analogues in the TP series that incorporate a modified or unmodified L-methionine sulfone amide at the C2 endo position on the camphor ring exhibit high affinity for OT receptors (ICs0= 1.3-15 nM) and good selectivity for binding to ...