Tandem Photocycloaddition−Retro-Mannich Fragmentation of Enaminones. A Route to Spiropyrrolines and the Tetracyclic Core of Koumine
摘要:
Intramolecular [2 + 2] photocycloaddition of beta-aminoalkylidene malonates gives transiently a cyclobutane which undergoes retro-Mannich fragmentation to a Delta(1)-pyrroline. The tandem sequence, exemplified in two series based on tryptamine and aminoethyl-1,4-cyclohexadiene, leads to a spiroindolopyrroline skeleton and to the nonindolenine portion of koumine.
Tandem Photocycloaddition−Retro-Mannich Fragmentation of Enaminones. A Route to Spiropyrrolines and the Tetracyclic Core of Koumine
摘要:
Intramolecular [2 + 2] photocycloaddition of beta-aminoalkylidene malonates gives transiently a cyclobutane which undergoes retro-Mannich fragmentation to a Delta(1)-pyrroline. The tandem sequence, exemplified in two series based on tryptamine and aminoethyl-1,4-cyclohexadiene, leads to a spiroindolopyrroline skeleton and to the nonindolenine portion of koumine.