Intramolecular carbolithiation of allyl o-lithioaryl ethers: a new enantioselective synthesis of functionalized 2,3-dihydrobenzofurans.
A new and easy method for the diastereoselective synthesis of 3-functionalized 2,3-dihydrobenzofuran derivatives from allyl 2-bromoaryl ethers is described. The key step of this transformation involves an intramolecular carbolithiation reaction of allyl 2-lithioaryl ethers. The substituents in both the allyl and the aryl moieties play an important and decisive role in stopping the reaction at the benzofuran thus avoiding a gamma-elimination reaction. Finally, this process is amenable to the synthesis of enantiomerically enriched compounds by using (-)-sparteine as a chiral inductor.
Barluenga
José
J
Instituto Universitario de Química Organometálica Enrique Moles, Unidad Asociada al C.S.I.C., Universidad de Oviedo, Julián Clavería 8, 33006-Oviedo, Spain. barluenga@uniovi.es
Fañanás
Francisco J
FJ
Sanz
Roberto
R
Marcos
César
C