Enzymatic activity catalysing exo-selective Diels–Alder reaction in solanapyrone biosynthesis

Abstract
The crude enzyme from Alternaria solani is able to catalyse the [4 + 2] cycloaddition of prosolanapyrone III 6 to the exo adduct solanapyrone A 1 whose optical purity is estimated as 92 ± 8% e.e. by HPLC analysis monitored using a CD spectrometer; this enzyme also catalyses the oxidation and [4 + 2] cycloaddition of prosolanapyrone II 5 to 1 with 99 ± 4% e.e.