Total synthesis of (±)-pentenomycin

A concise stereoselective route to (±)-pentenomycin 1 in 33% overall yield starting from the readily accessible Diels–Alder adduct 4 is reported. The key reaction involves decarbonylation of β-methoxy-α,β-unsaturated aldehyde 8 obtained from β-hydroxy-dimethylketal 6.