Regio- and Stereocontrolled-Synthesis of a Heterocycle Fragment Collection Using Palladium Catalyzed C-H Arylation.

Saturated heterocycles are valuable fragments in drug discovery due to their polarity, 3D structure, and potential for versatile binding modes, yet their controlled functionalization remains challenging. Existing methods often require pre-functionalized substrates and provide limited control over substitution patterns, restricting access to diverse exit vectors. Here, we report a campaign achieving systematic control over the position and orientation of exit vectors in heterocycles through the synthesis of a structurally diverse fragment collection using aminoquinoline-directed C-H functionalization. The study prioritizes five- and six-membered N-heterocycles, as well as rings with sulfonyl and difluoromethylene units. Aminoquinoline directing groups installed at C(2), C(3), or C(4) enable β-arylation, and are subsequently removed to reveal carboxylic acids, primary amides, primary alcohols, or nitriles. The resulting 44 fragments, now part of AbbVie's compound collection, combine structural novelty with favorable physicochemical properties. Finally, a simple script is provided for rapid analysis of fragment properties.