Total synthesis of (-)-cylindrocyclophane A facilitated by C-H functionalization.

Bosse, Aaron T; Hunt, Liam R; Suarez, Camila A; Casselman, Tyler D; Goldstein, Elizabeth L; Wright, Austin C; Park, Hojoon; Virgil, Scott C et al. · Science · 2024

basic_science · Level V

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Abstract

(-)-Cylindrocyclophane A is a 22-membered C<sub>2</sub>-symmetric [7.7]paracyclophane that bears bis-resorcinol functionality and six stereocenters. We report a synthetic strategy for (-)-cylindrocyclophane A that uses 10 C-H functionalization reactions, resulting in a streamlined route with high enantioselectivity and efficiency (17 steps). The use of chiral dirhodium tetracarboxylate catalysis enabled the C-H functionalization of primary and secondary positions, which was complemented by palladium-catalyzed C(sp<sup>2</sup>)-C(sp<sup>2</sup>) cross-couplings, resulting in the rapid formation of the macrocyclic core and all stereocenters with high regio-, diastereo-, and enantioselectivity. The use of a late-stage palladium-catalyzed fourfold C(sp<sup>2</sup>)-H acetoxylation installed the bis-resorcinol moieties. This research exemplifies how multilaboratory collaborations can produce substantial modernizations of complex total synthesis endeavors.