Synthesis of the Bioactive Benzochromenes Pulchrol and Pulchral, Metabolites of Bourreria pulchra

The parasites Leshmania mexicana and Trypanosoma cruzi cause serious health problems, and few efficient treatments are available. Recently, the two benzochromenes pulchrol (1) and pulchral (2) were reported from the roots of Bourreria pulchra, and especially 1 but also 2 was found to be active towards the parasites. In this paper, we present a total synthesis of 1 and 2 to facilitate their biological evaluation. The synthesis is mild, short, and high yielding and suitable for a structure-activity relationship study.