Tri-0-acetyl-D-ribofuranosyl)-Az-nonanoylguanine (18).-The 9 isomer 18 from the Florisil column was a solid foam: [a] 22d -43 (c 0.50, CHCls); nmr (DMSO-*) S 8.10 (s, H-8 of 0-18), 7.94 (s, H-8 of a-18), 5.95 (d, Jv.v = 5.5 Hz, H-V of 0-18) with H-V of a-18 not discernible above noise level, but perhaps at 6.3; the peak areas for H-8 of \ß are 1:6; uv max wras like that of 6; Rt 0.11 in TA.