Rhodium(II) Acetate Dimer

Typical Procedure:
Alkyne (0.2 mmol), TsN₃ (1.0 eq.), alkenyl alkyl ether (3.0 eq.), CuTC (10.0 mol%), Rh₂(OAc)₄ (1.0 mol%), and DCE (0.2 M) are added to an oven-dried test tube under nitrogen atmosphere. The reaction mixture is stirred at ambient temperature for 3 h and then, heated at 80 °C for 4–13 h. After the reaction mixture is filtered through short path of celite with CH₂Cl₂, the filtrate is concentrated under reduced pressure. The residue is purified by silica gel column chromatography (ethyl acetate–hexane) to give pyrrole derivatives (Y. 65–81%).

Typical Procedure: A flask is charged with allyl alcohol (0.10 mmol, 1.0 eq.), Rh2(OAc)4 (2.0 mol%) and 4A MS (0.1 g) in toluene (1.5 mL), the reaction mixture is stirred at 45℃, and a solution of the diazo compound (0.20 mmol) in toluene (0.5 mL) is added to the reaction mixture over a period of 1 h through a syringe pump. After completion of the addition, piperidine (2.0 eq.) is added and the reaction mixture is stirred for additional 5-10 h (reaction completion is monitored by TLC) at 45℃. The reaction mixture is purified by flash chromatography on silica gel (EtOAc : light petroleum ether = 1 : 50 to 1 : 20) to give the pure product.