1. a U. S. Patent applied for.
2. (b) Ara-A is the abbreviation of 9-(β-D-arabinofuranosyl)adenine, J. D. Howells and A. Ryder (Parke, Davis and Company), U. S. Patent 3,616,208, 26 October, 1971.
3. L. Hough, J. Chem. Soc., 3066 (1953).
4. a Spectra were determined in deuterium oxide at 100 MHz with chemical shifts reported in ppm from external tetramethylsilane.
5. b Signal assignments were confirmed by spin-decoupling studies at 100 MHz.