Asymmetric Friedel-Crafts Reactions: Catalytic Enantioselective Addition of Aromatic and Heteroaromatic C-H Bonds to Activated Alkenes, Carbonyl Compounds, and Imines

Abstract

The development and scope of catalytic enantioselective addition of aromatic and heteroaromatic C-H bonds to α,β-unsaturated alkenes, carbonyl compounds, and imines are presented. α,β-Unsaturated alkenes, 4-substituted 2-oxo-3-butenoate esters and alkylidene malonates react with indoles, furans and electron-rich aromatic compounds in the presence of chiral bisoxazoline-copper(II) complexes to give the Friedel-Crafts alkylation adduct in moderate to high yields and with up to >99.5% ee. Chiral bisoxazoline-copper(II) complexes can also catalyze the enantioselective addition of especially electron-rich aromatic compounds to activated carbonyl compounds such as glyoxylates and trifluoropyruvate to give e.g. optically active aromatic mandelic acid esters in good yields and enantioselectivities. Electron-rich aromatic compounds and heteroaromatic compounds react in an enantioselective fashion with activated N-protected α-imino esters to give optically active aromatic and heteroaromatic α-amino acid derivatives using chiral BINAP­-copper(I) complexes as the catalyst.

Key words

asymmetric catalysis - Friedel-Crafts reactions - al­kenes - carbonyl compounds - imines

References

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