Scheme 10. Dixon's Au(i)-catalysed cascade. Reagents and conditions: (1) AuPPh₃Cl/AgOTf (1%), 26b, 28a, toluene, rt, 3 h, then reflux, 2 d, d.r. 2 : 1, 81% [R¹ = H, R² = CH₂Ph, X = CH₂]; (2) AuPPh₃Cl/AgOTf (1%), 26a, 28a, toluene, rt, 3 h then reflux, 1 d, 91%; (3) AuPPh₃Cl/AgOTf (1%), 26b, 28a, toluene, 75 °C, then reflux 1 d, d.r. 3 : 1, 64% [R¹ = H, R² = Me, X = O]; (4) AuPPh₃Cl/AgOTf (1%), 26b, 28b, xylene, 75 °C, 3 h, then 125 °C, 1 d, d.r. 1 : 5 : 1, 97%, [R¹ = n-pentyl, R² = H, X = O]; (5) AuPPh₃Cl/AgOTf (1%), 26b, 28b, toluene, 75 °C, 3 h, then reflux, 2 d, d.r. 1 : 1 : 5, 82%, [R¹ = H, R² = CH₂Ph, X = CH₂]; (6) AuPPh₃Cl/AgOTf (1%), 26a, 28b, toluene, 75 C, 3 h, reflux, 1 d, 87%.