Palladium-Catalyzed Cross-Coupling Reactions between Dihydropyranylindium Reagents and Aryl Halides. Synthesis of C-Aryl Glycals

Palladium(0)-catalyzed cross-coupling reactions between tris(dihydropyranyl)indium 1 and aryl halides 2 have been investigated. Aryl iodides and electron-deficient aryl bromides couple efficiently with the in situ-generated indium reagents in the presence of 1−5 mol % Cl₂Pd(PPh₃)₂ to produce substituted dihydropyrans 3 with minimal (<10%) dimer (4) formation. Organoindium reagents derived from d-glucal also undergo cross couplings with aryl iodides to produce C-aryl glycals.