Scheme 12. Taylor's cascade for the synthesis of polycyclic compounds. Reagents and conditions: (1) 4 Å MS, CHCl3, Δ; 41a: 96% [R1 = Py, R2,R3 = –(CH2)3–, R4,R5 = allyl]; 41b: 83% [R1 = Py, R2,R3 = –(CH2)3–, R4,R5 = –(CH2)4–]; 41c: 56% [R1= CO2Et, R2,R3 = –(CH2)2–, R4,R5= –(CH2)4–]; 41d: 67% [R1 = Py, R2 = trans-3-octane, R3 = H, R4, R5 = –(CH2)4–]; 41e: 39% [R1 = CO2Et, R2,R3 = –(CH2)3–, R4 = Bn, R5 = but-3-enyl]. Py = 2-pyridyl.
