New Carbanionic Access to 3-Vinylindoles and 3-Vinylbenzofurans
摘要:
[GRAPHICS]A simple route to 3-vinylbenzofurans, 3-vinyifuropyridines, and 3-vinylindoles from readily accessible acetylenic precursors is described. A standard halogen-lithium exchange triggers an irreversible! addition on the triple bond, according to a 5-exo-dig heterocyclization process, followed by a lithium ethoxide elimination. A final isomerization of the exocyclic allene provides a 1,3-dienic system that can react with acrylates, in thermal or hyperbaric conditions, to provide the expected [4+2] cycloadducts.
New Carbanionic Access to 3-Vinylindoles and 3-Vinylbenzofurans
摘要:
[GRAPHICS]A simple route to 3-vinylbenzofurans, 3-vinyifuropyridines, and 3-vinylindoles from readily accessible acetylenic precursors is described. A standard halogen-lithium exchange triggers an irreversible! addition on the triple bond, according to a 5-exo-dig heterocyclization process, followed by a lithium ethoxide elimination. A final isomerization of the exocyclic allene provides a 1,3-dienic system that can react with acrylates, in thermal or hyperbaric conditions, to provide the expected [4+2] cycloadducts.