Disclosed herein are compounds of formula (I) and therapeutic methods of treatment with compounds of formula (I), wherein L 1 , L 2 , L 4 , R 1 , R 4 , R 5 , R 6 , and s are as defined in the specification. Compounds of formula (I) are EP4 agonists useful in the treatment of glaucoma, neuropathic pain, and related disorders.