title: An organocatalytic Mannich/denitration reaction for the asymmetric synthesis of 3-ethylacetate-substitued 3-amino-2-oxindoles: formal synthesis of AG-041R.
abstract: The highly enantioselective organocatalytic addition of ethyl nitroacetate to isatin-derived N-Boc ketimines (Boc = tert-butoxycarbonyl), followed by the removal of the nitro group, is described. The scalable reaction sequence leads to the title compounds as important intermediates of pyrroloindoline alkaloids and related drugs in excellent yields and enantioselectivities. The synthesis of the hexahydrofurano[2,3-b]indole skeleton, the spirocarbamate oxindole unit, and the formal synthesis of AG-041R have been carried out to demonstrate the synthetic utility of this protocol.
authors: Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, 52074 Aachen (Germany), Fax: (+49) 241-809-2127 http://www.oc.rwth-aachen.de/akenders/AKEN_D.HTM.
authors: Kun
authors: K
authors: Zhao
authors: Tao
authors: T
authors: Shu
authors: Jiaqi
authors: J
authors: Jia
authors: Gerhard
authors: G
authors: Raabe
authors: Dieter
authors: D
authors: Enders
mesh_terms: D002384:Catalysis; D005663:Furans / Q000737:chemistry; D007097:Imines / Q000737:chemistry*; D026121:Indole Alkaloids / Q000737:chemistry*; D007211:Indoles / Q000138:chemical synthesis* / Q000737:chemistry; D015394:Molecular Structure; D009570:Nitriles / Q000737:chemistry*; D000078183:Oxindoles; D013141:Spiro Compounds / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: C551521:3-amino-2-oxindole; C109755:AG-041R; D005663:Furans; D007097:Imines; D026121:Indole Alkaloids; D007211:Indoles; D009570:Nitriles; D000078183:Oxindoles; D013141:Spiro Compounds; C542835:ketimine
keywords: Mannich reaction; asymmetric synthesis; ketimines; organocatalysis; oxindoles