Synthesis of (-)-longithorone A: Using organic synthesis to probe a proposed biosynthesis
AUTOR(ES)
Morales, Carl A.
FONTE
National Academy of Sciences
RESUMO
We present a full report of our enantioselective synthesis of (-)-longithorone A (1). The synthesis was designed to test the feasibility of the biosynthetic proposal for 1 put forward by Schmitz involving intermolecular and transannular Diels–Alder reactions of two [12]-paracyclophane quinones. We have found that if the biosynthesis does involve these two Diels–Alder reactions, the intermolecular Diels–Alder reaction likely occurs before the transannular cycloaddition. The intermolecular Diels–Alder precursors, [12]-paracyclophanes 38, 49, 59, and 60, were prepared atropselectively, providing examples of ene–yne metathesis macrocyclization. The 1,3-disubstituted dienes produced from the macrocyclizations represent a previously unreported substitution pattern for intramolecular ene–yne metathesis. Protected benzylic hydroxyl stereocenters were used as removable atropisomer control elements and were installed by using a highly enantioselective vinylzinc addition to electron-rich benzaldehydes 26 and 27.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=514430Documentos Relacionados
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