Fig. 4: Substrate scope of alkyl boronic esters.

^a1 (0.40 mmol, 2.0 equiv.), 2 (0.40 mmol, 2.0 equiv.), 3a (0.20 mmol, 1.0 equiv.), Pd₂(dba)₃ (0.005 mmol, 2.5 mol%) and L8 (0.012 mmol, 6 mol%) in THF and DCM at 60 ^oC. Only cis-cyclobutane isomers were observed in this reaction unless otherwise noted. ^bUsing Pd(PPh₃)₄ and L12 in THF at 40 ^oC.