... The position of the acetyl group in 2i is assigned on the basis of nmr data: the chemical shift of the C-5 protons (6 3.90 t) is similar to that of li (6 3.96) and lj (6 3.95). ... Journal of Medicinal Chemistry, 1975, Vol. 18, No. ... 92 Journal ofMedcccnal C hernist ~ , 1975, Vul 18, ,Vo 1 i c - ...