Cryptobeilic acid D is an antimalarial natural product from <i>Beilschmiedia cryptocaryoides</i> related to the endiandric acids. We have achieved a concise synthesis of the two tetracyclic scaffolds found in the cryptobeilic and endiandric acids using iterative Suzuki-Miyaura couplings between boronic acids and MIDA-protected boronates. This synthesis demonstrates the first successful creation of a conjugated (<i>E,Z,Z,E</i>) tetraene using MIDA boronates, which triggers an 8π-6π electrocyclization cascade. An intramolecular Diels-Alder reaction then furnishes either a fused or bridged tetracycle. Geometric considerations for Suzuki-Miyaura couplings and competing regiochemical outcomes for Diels-Alder reactions will be discussed.

Expedient synthesis of cryptobeilic/endiandric tetracycles

251st National Meeting (2016)

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