Synthesis of carbocyclic homo-N-nucleosides from iridoids

Two iridoid glucosides, antirrhinoside (1) and catalpol (2), were converted into selectively protected polysubstituted cyclopentylmethanols, which wer e subsequently used to prepare carbocyclic homo-N-nucleosides (5, 6 and 14) . A purine moiety was introduced either by the Mitsunobu reaction or by sub stitution of a primary triflate with the tetrabutylammonium salt of 6-iodop urine. The latter method was superior with regard to both ease of purificat ion and yield. The N-9 vs. N-7 regioselectivity of the salts of different 6 -substituted purine derivatives was briefly investigated.