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

Abstract

A new [RhA C H T U N G T R E N N U N G (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 À 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.

Cycloisomerization of 1,n‐Enynes: Challenging Metal‐Catalyzed Rearrangements and Mechanistic Insights

“…(77)]. [94] An intramolecular version of this reaction was recently reported, in which trieneyne 246 with a Si À O unit was cyclized to the two isomeric tricycles 247 a and 247 b [Eq. (78), Np: naphthalene].…”

Cycloisomerisierungen von 1,n‐Eninen: faszinierende metallkatalysierte Umlagerungen und mechanistische Einblicke

“…(61) [94] Vor kurzem wurde eine intramolekulare Variante dieser Reaktion beschrieben, bei der das eine Si-O-Einheit enthaltende Trienin 246 zu den beiden isomeren Tricyclen 247 a und 247 b reagierte [Gl. (78), Np: Naphthalin].…”

“…Als Enine können in dieser Reaktion nur stickstoffverbrückte wie 290 eingesetzt werden [Gl. (94)], und die Enantioselektivität ist vom Substrat abhängig. So wurde mit einer chlorsubstituierten Arylgruppe an der Doppelbindung das Produkt 291 mit 74 % ee erhalten, während ein Naphthylsubstituent eine starke Abnahme des ee-Werts verursachte.…”

Synthesis of Colchicinoids and Allocolchicinoids through Rh(I)-Catalyzed [2+2+2+1] and [2+2+2] Cycloadditions of o-Phenylenetriynes with and without CO

“…To rapidly implement molecular complexity from readily available simple starting materials, transition metal-catalyzed carbocyclization and cycloaddition reactions are recognized as synthetically very important processes. − Considerable advances have been made recently in the development of higher order cycloaddition reactions such as [2+2+2+1], − [3+3+1], [2+2+2+2], − [4+2+2], − [5+2+1], − and [5+1+2+1] processes. Various polycyclization reactions have been employed for the construction of natural and unnatural fused-ring systems that can be further elaborated into specific targets.…”