Modular Synthesis of Stereodefined Benzocyclobutene Derivatives via Sequential Cu- and Pd-Catalysis

Benzocyclobutenes (BCBs) are of growing interest in materials and medicinal chemistry, although general routes for their provision remain underexplored. A modular, divergent, and stereoselective Cu- and Pd-catalyzed assembly/cyclization sequence allows the synthesis of densely functionalized BCBs, from readily accessible imine, allene, and diboron precursors. Preliminary results have identified enantioselective conditions for our protocol and high-lighted, for example, its applicability to the synthesis of BCB-containing peptides. By simple variation of experimental conditions or substrate modification, our strategy was expanded to deliver indoline and quinoline derivatives, suitable for further manipulations.