Abacavir enantiomer

Abacavir enantiomer (CAS 136470-79-6) is the non-pharmacologically active stereoisomer of the antiretroviral drug Abacavir, differing in configuration at the chiral center of the cyclopropylmethyl substituent. It retains the core 1,3,6-triazine ring fused to a pyrimidine moiety, with a (S)-configured cyclopropylmethyl group instead of the parent drug’s (R)-configuration. This structural inversion disrupts optimal binding to HIV reverse transcriptase. Synthesized as a byproduct during enantioselective resolution processes, it serves as a critical HPLC reference standard for enantiomeric purity analysis in Abacavir API manufacturing.