Concise synthesis of (25S)-Δ4-dafachronic acid and desulfated boophiline enabled by photoinduced decarboxylative allylation and asymmetric hydrogenation

Abstract

(25S)-Δ⁴-Dafachronic acid and boophiline exhibit intriguing bioactivities. However, the C-25 configuration of boophiline remains undetermined. Here, we present their concise synthesis from readily available bile acids. The synthesis featured a photoinduced decarboxylative allylation followed by an asymmetric hydrogenation. A stereodivergent synthesis of both C-25 diastereomers of desulfated boophiline enabled further confirmation of its absolute configuration. Furthermore, the decarboxylative allylation was applied to the late-stage functionalization of a range of complex natural products and pharmaceuticals.