Total Synthesis of (+/-) Carbocyclic Polyoxin C and Its alpha-Epimer.

Carbocyclic polyoxin C (2) and its alpha-epimer 3 were synthesized in racemic form in an efficient and diastereodivergent fashion from cis-4-(N-tert-butylcarbamoyl)cyclopent-2-en-1-ol (5a). This synthesis features a Pd(0)-catalyzed substitution reaction, a novel, mild reduction of an alpha-nitro ester to an amino acid ester, and an improved procedure for uracil ring formation.