Tandem photocycloaddition-retro-mannich fragmentation of enaminones. A route to spiropyrrolines and the tetracyclic core of koumine.
[reaction: see text] 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.
White
James D
JD
Department of Chemistry, Oregon State University, Corvallis, Oregon 97331-4003, USA. james.white@oregonstate.edu
Ihle
David C
DC
D000577:Amides / Q000737:chemistry*; D002384:Catalysis; D003500:Cyclization; D026121:Indole Alkaloids / Q000138:chemical synthesis* / Q000737:chemistry; D015394:Molecular Structure; D010777:Photochemistry; D011758:Pyrroles / Q000138:chemical synthesis* / Q000737:chemistry*; D013141:Spiro Compounds / Q000138:chemical synthesis*; D013237:Stereoisomerism
D000577:Amides; D026121:Indole Alkaloids; D011758:Pyrroles; D013141:Spiro Compounds; C515085:koumine; C013231:pyrroline