Fig. 3: Construction of phosphine-containing 1,2,3-trisubstituted cyclobutane scaffolds^a,b.

^aConditions B: 0.2 mmol BCB 1, 2.0 equiv. diphenyl phosphine, 1.0 equiv. LiBr and 10 mol% CuBr₂ in 2.0 mL DMF at 60 °C for 24 h. ^bIsolated yield. ^c1.0 mmol scale, 4a: d.r. = 15:1.^dRun at 25 °C.