Synthesis and antiviral evaluation of novel 6'(alpha)-methyl-branched Carbovir analogues.

A new stereoselective synthesis of 6'-branched Carbovir analogues was accomplished in this study. The introduction of a methyl group in the requisite 6'(alpha)-position was carried out using an ester enolate alkylation (LHMDS, CH3I). The desired cyclopentenol 7 was synthesized via a Felkin-Anh-controlled Grignard addition and ring-closing metathesis using second-generation Grubbs' catalyst. The natural bases (adenine, cytosine) were efficiently coupled using a Pd(0) catalyst. When the synthesized compounds were examined for their activity against several viruses such as the HIV-1, HSV-1, HSV-2, and HCMV, the adenine analogue 12 exhibited moderate antiviral activity against the HCMV.