A Biomimetic Synthesis of (±)‐Basiliolide B

Abstract

A highly diastereoselective and practical biomimetic total synthesis of (AE)-basiliolide B has been achieved through the study of the two proposed biosynthetic pathways (Omethylation and O-acylation) for the unprecedented 7methoxy-4,5-dihydro-3H-oxepin-2-one (C ring). The synthesis featured a cyclopropanation/ring opening strategy for establishing the stereogenic centers at C8 and C9, a biomimetic 2pyrone Diels-Alder cycloaddition for the synthesis of the ABD ring system, and finally a highly efficient biomimetic intramolecular O-acylation for the C ring formation. This result provides an important perspective on the biosynthetic origin of the unprecedented 7-membered acyl ketene acetal moiety of the C ring.

Orthogonally Protected Diaminoterephthalate Scaffolds: Installation of Two Functional Units at the Chromophore

“…As the second target compound 28 , we aimed at the preparation of an analogue of compound 1 with the functional units cyclooctyne and maleimide now one bound to the 3-aminopropylamino and one to the 2-carboxyethylamino moiety of scaffold 4 (Scheme ). For this purpose, the allyl ester of compound 4 was deprotected by palladium-catalyzed allylic substitution with pyrrolidine as nucleophile to quantitatively furnish the acid 23 , which was subsequently amidated with maleimide building block 24 , accessed according to a literature procedure . Compound 25 was obtained in 87% yield.…”