A two-step four-component queuing cascade involving a Heck coupling, π-allylpalladium trapping and Diels–Alder reaction

Abstract

Palladium-catalyzed cross-coupling of bicyclopropylidene ( 1 ) with iodoethene ( 11 ) in the presence of a secondary amine 12 provides allylidenecyclopropanes 13 which undergo immediate Diels–Alder reactions upon addition of dienophiles 14– 18 to provide 8-(1′-aminoethyl)-substituted spiro[2.5]oct-7-ene derivatives 23a– 26a in 29–66% yield. The same one-pot, two-step queuing cascade can be carried out with other iodoalkenes including cyclic ones and with cyclic dienophiles such as N-arylmaleinamides 19– 22 and N-phenyl-triazolinedione 37 to furnish highly substituted spiro[2.5]oct-4-enes and spirocyclopropanated heterobicycles 47a– 49a , 41a– 46a (17–50%). Spirocyclopropanated heterobicycles such as 55 , 56 (25 and 38% yield, respectively) can also be obtained by an inter-intra-intra-intermolecular version of this queuing cascade involving 1-hydroxyethyl- and 1-aminoethyl-substituted iodoethenes 53 , 54 .