Rhodium‐Catalyzed [4+2+2] Cycloaddition Reaction of Two Enynes or Diynes with One Diene to Give Eight‐Membered Ring Compounds

Abstract A new [Rh(cod)Cl]2/AgX (cod=1,5‐cyclooctadiene)‐catalyzed intermolecular [4+2+2] cycloaddition reaction between two enynes with one diene, and between two diynes and one diene has been developed. This is the first example of a rhodium‐catalyzed trimolecular and three‐component [4+2+2] cycloaddition to form eight‐membered ring compounds. The yield of the reaction was highly dependent upon the counteranion and the reaction medium. The best yields were obtained when the reaction was carried out in toluene with OTf− anions. The regioselectivity was highly dependent upon the substrates. Relatively high regioselectivities were obtained for the cycloaddition of two enynes with one diene. In some cases, only one regioisomer was obtained. However, the regioselectivities for the cycloaddition of two diynes with one diene were rather poor. The use of a syringe pump in the slow addition of reactants slightly enhanced the regioselectivity.