Densely-functionalized bicyclic cyclopentanones by combined photoinduced 6-<i>endo-trig</i> Giese additions and mild aldol cyclizations.

ABSTRACT: Polycyclic scaffolds are central to numerous natural products and pharmaceuticals, motivating concise, stereocontrolled routes to their construction. We report a photoredox-enabled synthesis of trans-fused [n.3.0] bicyclic ketones (n = 4, 5, 10) from malonate-derived enol ethers. α-Brominated intermediates, formed by acylation with 2-bromo-2-methylpropanoyl bromide, undergo radical cyclization under two complementary conditions: (i) acridinium orange (AOH⁺) with Hantzsch ester (HE) at 455 nm, or (ii) photoexcited HE alone at 365 nm. Both modes trigger 6-endo-trig Giese addition, C-O bond fragmentation, and hydrogen-atom transfer to α-branched cyclic ketones that ring-close under mild Brønsted or Lewis acid activation to trans-fused products wit

SUBMITTER: Vinas-Lobez J 

PROVIDER: S-EPMC12870345 | biostudies-literature | 2026 Jan

REPOSITORIES: biostudies-literature