What question did this study set out to answer?

To explore a bimetallic catalytic system for synthesizing pyridine-fused benzophosphole oxides via C-H activation.

January 24, 2026Organic Letters0 citations

Pd/Tl Bimetal-Catalyzed C3(5)–H Activation of Pyridine Derivatives Enables Access to Pyridine-Fused Benzophospholes and Their Transformation into Seven-Membered Phosphepines

TYTakahiro Yamada TSTatsuya Sakaguchi YHYoshimitsu Hashimoto

Key Points

To explore a bimetallic catalytic system for synthesizing pyridine-fused benzophosphole oxides via C-H activation.
Utilized a Pd/Tl catalytic system for C3(5)–H activation.
Conducted intramolecular dehydrogenative coupling of 4-(diphenylphosphinoyl) pyridines.
Transformed resultant benzophosphole oxides into seven-membered phosphepine oxides using Ni/Al catalysts.
Achieved synthesis of pyridine-fused benzophosphole oxides with yields up to 98%.
Successfully converted benzophosphole oxides into phosphepine oxides.

Abstract

A Pd/Tl bimetallic catalytic system for the efficient synthesis of pyridine-fused benzophosphole oxides via a C-H functionalization strategy has been developed. The synergistic action of the palladium catalyst and Tl(OCOCF3)3 enables C3(5)-H activation and intramolecular dehydrogenative coupling of 4-(diphenylphosphinoyl) pyridines, affording a series of pyridine-fused benzophosphole oxides in up to 98% yield. Remarkably, further transformations of these pyridine-fused benzophosphole oxides into seven-membered phosphepine oxides were realized via Ni/Al bimetallic catalytic system.

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