... Please enable JavaScript to use all the features on this page. Tetrahedron Letters. Volume 41, Issue 33, 12 August 2000, Pages 6309–6312. Cover image Cover image. ... 1999, 40, 3651–3654. (c) Enkephalin analogs: Sreder, K.; Zhang, L.; Goodman, M. Tetrahedron Lett. ...