Enantiomerically pure (+)- and (-)-carbocyclic thymidine, (-)-carbocyclic 3'-epi-thymidine, (+)-carbocyclic 3'-deoxy-3'-azidothymidine, (+)-carbocyclic 2,3'-O-anhydrothymidine, (+)-carbocyclic 3'-0,6'-methylenethymidine, anc (+)-(6'S)-carbocyclic 6'-methylthymidine were synthesized in a stereospecific manner from common chiral pools of (+)-(li?,5S)- and (-)-(lS,5R)-2-oxabicyclo[3.3.0]oct-6-en-3-one and evaluated for antiviral activity. (+)-Carbathymidine and, to a lesser extent, (+)-carbocyclic 2'-deoxyadenosine proved to be effective against HSV-1 [minimum inhibitory concentration (MIC): 0.2 and 2 μg/mL, respectively] and HSV-2 (MIC: 2 and 20 μg/mL, respectively), but virtually inactive against TK-HSV-1 (MIC: 40 and 100 μg/mL, respectively). (+)-Carbathymidine was alsc active against vaccinia virus (2 μg/mL). None of the compounds had a specific effect on the replication of HIV or other RNA viruses. © 1990, American Chemical Society. All rights reserved.