title: Synthesis of 2-alkylidenepyrrolidines, pyrroles, and indoles by condensation of silyl enol ethers and 1,3-bis-silyl enol ethers with 1-azido-2,2-dimethoxyethane and subsequent reductive cyclization.
abstract: The condensation of 1,3-bis-silyl enol ethers with 1-azido-2,2-dimethoxyethane and subsequent reductive cyclization allowed an efficient regio- and diastereoselective synthesis of a variety of 2-alkylidene-4-methoxypyrrolidines. The thermal elimination of methanol resulted in the formation of functionalized pyrroles. Similarly, 2,3,3a,4,5,6-hexahydro-2,3-benzopyrroles were prepared and transformed into 4,5,6,7-tetrahydro-2,3-benzopyrroles. In contrast, treatment of 2-alkylidenepyrrolidines with trifluoroacetic acid resulted in formation of indoles by [4 + 2] cycloaddition and subsequent extrusion of a nitrogen atom.
authors.affiliation: Institut für Chemie, Universität Rostock, Albert-Einstein-Str. 3a, 18051 Rostock, Germany.
authors.forename: Esen
authors.initials: E
authors.lastname: Bellur
authors.forename: Helmar
authors.initials: H
authors.lastname: Görls
authors.forename: Peter
authors.initials: P
authors.lastname: Langer