A total synthesis of bioactive tetracyclic natural product paracaseolide A, embodying an architecturally unusual oxa-bowl framework, has been accomplished from commercially available 5-methyl-2-furfural. The key step involving a thermal [4+2]-dimerization of an appropriately crafted 5-methyl-3- alkenylbutenolide is shown to proceed in a stepwise manner. © 2013 Elsevier Ltd. All rights reserved.