RESUMO
A bottom-up synthesis of lamellarins G, J, L, and Z was achieved via one-pot halogen dance/Negishi coupling of a lithiated dibromopyrrole derivative. The easily accessible dibromopyrrole bearing an ester moiety underwent halogen dance smoothly at -78 °C within 10 min. The resultant α-pyrrolyllithium was transmetalated to the corresponding organozinc species, which was then coupled with an aryl iodide in the presence of catalytic palladium to provide the fully substituted pyrrole. Subsequent halogen-lithium exchange was performed to incorporate a boronate group exclusively at the ß position proximal to the ester moiety. This synthetic intermediate allowed stepwise diarylation for the total synthesis of lamellarins G, J, L, and Z.
Assuntos
Halogênios , Catálise , Halogênios/química , Paládio/química , Pirróis/químicaRESUMO
A convergent total synthesis of lamellarins S and Z is described. The synthesis features a halogen dance of an easily accessible α,ß-dibromopyrrole promoted by an ester moiety. The resultant ß,ß'-dibromopyrrole undergoes a ligand-controlled Suzuki-Miyaura coupling to provide a range of diarylated pyrrole derivatives. The established synthetic method was also applicable to the synthesis of ningalin B and lukianols A and B.