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.
Conjugate addition of aromatic amines to ethenetricarboxylates
作者:Shoko Yamazaki、Machiko Yamamoto、Akiko Sumi
DOI:10.1016/j.tet.2006.12.058
日期:2007.3
The conjugateaddition of amines is considered to be a useful reaction in synthetic organic chemistry. The reaction of reactive electrophilic olefins, ethenetricarboxylates, and aromaticamines with and without catalytic Lewis acids such as ZnCl2 and ZnBr2 at room temperature gave amine adducts in high yields. The products were converted to α-amino acid, dl-aspartic acidderivatives. Using Lewis acids
A Lewis acid-promoted cyclization of ethenetricarboxylate derivative aromatic compounds. Novel syntheses of oxindoles and benzofuranones via Friedel–Crafts intramolecular Michael addition
A novel cyclization reaction of ethenetricarboxylate derivative aromatic compounds in the presence of various Lewis acids gave benzo-annulated cyclic compounds such as oxindole and benzofuran derivatives via Friedel-Craftsintramolecular Michael addition in high yields. For example, the reaction of diethyl 2-[(N-methyl-N-phenylcarbamoyl)methylene]malonate (1a) in the presence of ZnCl2 at room temperature