Total Synthesis of Pyrophen and Campyrones A-C.

The first total syntheses of the natural products pyrophen and campyrones A-C, isolated from the fungus Aspergillus niger, have been achieved in six steps starting from commercially available N-Boc amino acids. Key steps in this sequence include a vinylogous Claisen condensation to achieve fragment coupling and a dioxinone thermolysis/cyclization cascade to form the α-pyrone ring. The route described herein afforded the natural products in 15-25% overall yield, furnishing sufficient material for testing in biological assays.