A Facile Route to Bridgehead Disubstituted Bicyclo[1.1.1]pentanes Involving Palladium-Catalyzed Cross-Coupling Reactions

3-Alkylbicyclo[1.1.1]pent-1-yl Grignard reagents have been coupled with bromoarenes in the presence of catalytic amounts (0.8–2.0 mol.%) of PdCl2(dppf) in diethyl ether containing 1,4-dioxane as a co-solvent at room temperature. The yields of the coupling step range from 73% to 98%. By using di- or tribromoarenes, coupling products of types 10 and 11 have been obtained. The X-ray structures of four model compounds (4a, 4d, 4j, 4n) have been determined, each of which shows a short, nonbonded C1–C3 distance in the bicyclo[1.1.1]pentyl subunit of about 1.89 Å.