Zinc- and Indium-Promoted Conjugate Addition−Cyclization Reactions of Ethenetricarboxylates with Propargylamines and Alcohol: Novel Methylenepyrrolidine and Methylenetetrahydrofuran Syntheses
摘要:
A new zinc- and indium-promoted conjugate addition-cyclization reaction to afford nitrogen- and oxygen-containing five-membered heterocycles has been developed. Reaction of ethenetricarboxylates with propargylamines (1 equiv) in the presence of ZnBr2 or InBr3 afforded methylenepyrrolidines in high yields. The stoichiometric use of ZnBr2 or InBr3 at room temperature and the catalytic use of lnBr(3)(-) Et3N at 80 degrees C were effective. Reaction of ethenetricarboxylates with propargyl alcohol in the presence of ZnBr2, or InBr3 afforded methylenetetrahydrofurans.
Enantioselective Friedel–Crafts reactions of ethenetricarboxylates and substituted pyrroles and furans and intramolecular reaction of benzene derivatives
Compared to enantioselective Friedel-Crafts reactions of indoles, reactions of alkylidene malonates with monocyclic aromatic compounds generally proceed with low enantioselectivity. The Friedel-Crafts reactions of ethenetricarboxylates 1 and monocyclic heteroaromatic compounds, such as substituted pyrroles and furans were investigated. The reaction of 1 with 2,4-dimethylpyrrole in the presence of a chiral bis-oxazoline-copper(II) complex (10 mol %) in tetrahydrofuran at room temperature gave alkylated products in up to 72% ee. The reaction of 1 with 2-substituted furans gave alkylated products in 46-62% ee. The absolute stereochemistry of the furan Friedel-Crafts product 7e was determined by transformation to the known 2,3-dimethylbutyric acid. The intramolecular reaction of benzene derivatives gave cyclized products up to 56% ee. (C) 2009 Elsevier Ltd. All rights reserved.
Catalytic Enantioselective Friedel−Crafts/Michael Addition Reactions of Indoles to Ethenetricarboxylates
作者:Shoko Yamazaki、Yuko Iwata
DOI:10.1021/jo052041p
日期:2006.1.1
The Friedel-Crafts reaction is an important reaction for the formation of new C-C bonds. Recently, catalytic enantioselective Friedel-Crafts reaction of alkylidene malonates has been reported. However, the substituents in alkylidene malonates are limited. To explore new substituents such as carboxyl and carbonyl groups, catalytic enantioselective Friedel-Crafts reactions of reactive ethenetricarboxylates and acyl-substituted methylenernalonates I were investigated. The reaction of 1 with indoles in the presence of catalytic amounts of chiral bisoxazoline copper(II) complex (10%) in THF at room temperature gave alkylated products in high yields and up to 95% ee. The enantioselectivity can be explained by the secondary orbital interaction on approach of indole to the less hindered side of the 1-Cu(II)-ligand complex.
Zinc- and Indium-Promoted Conjugate Addition−Cyclization Reactions of Ethenetricarboxylates with Propargylamines and Alcohol: Novel Methylenepyrrolidine and Methylenetetrahydrofuran Syntheses
A new zinc- and indium-promoted conjugate addition-cyclization reaction to afford nitrogen- and oxygen-containing five-membered heterocycles has been developed. Reaction of ethenetricarboxylates with propargylamines (1 equiv) in the presence of ZnBr2 or InBr3 afforded methylenepyrrolidines in high yields. The stoichiometric use of ZnBr2 or InBr3 at room temperature and the catalytic use of lnBr(3)(-) Et3N at 80 degrees C were effective. Reaction of ethenetricarboxylates with propargyl alcohol in the presence of ZnBr2, or InBr3 afforded methylenetetrahydrofurans.