HIGHLY STEREOSELECTIVE TOTAL SYNTHESES OF 2,5-ANHYDRO-3-DEOXY-D-HEXONIC AND 2,5-ANHYDRO-4-DEOXY-D-HEXONIC ACIDS AND OF THE RELATED DEOXYADENOSINES-C

(1R,2S,4R)-2-Cyano-7-oxabicyclo[2.2.1]hept-5-en-2-yl (1S)-camphanate (5) has been converted into 2,5-anhydro-3-deoxy-D-ribo-hexonic acid (8, eight steps, 38%) and 2,5-anhydro-3-deoxy-Deoxy-hexonic acid (9, seven steps, 40%). Similarly, (lS,4S)-7-oxabicyclo[2.2.1]hept-5-en-3-one (-)6, derived from (1S,2R,4S)-2-cyano-7-oxabicyclo[2.2.1]hept-5-en-2-yl (1R-camphanate (7)) was converted into 2,5-anhydro-4-deoxy-D-ri6o-hexonic acid (10, nine steps, 29%) and 2,5-anhydro-4-deoxy-D-xy/o-hexonic acid (11, eight steps, 31%). The methods exploit the high region selectivity of the electrophilic additions of the C=C double bonds in 7-oxabicyclo-[2.2.1]hept-5-en-2-yl derivatives 5 and 7 (“naked sugars”) and the high exo-face preference for the hydride reduction of 5- and 6-chloro-7-oxabicyclo(2.2.1]hept-5-en-2-ones (21,35). 2'-Deoxyadenosine-C (12) and cordycepin-C (14) were derived from 8 and 10, respectively. Similarly, the corresponding 2'- and 3'-epimers 13 and 15 (C-nucleosides deriving from 2-deoxy- and 3-deoxy-β-D-threo-pentofuranose, respectively) were obtained in few steps and with high stereo selectivity from 9 and 11, respectively. © 1990, American Chemical Society. All rights reserved.