22181-94-8 Benin Butocin Butocine Glycine, N-[1-oxo-5-(1H-purin-6-ylthio)pentyl]-, ethyl ester Glycine, N-[5-(purin-6-ylthio)valeryl]-, ethyl ester N-[.delta.-(6-Purinylthio)valeryl]glycine ethyl ester NSC172755