Organocatalytically Generated Donor–Acceptor Cyclopropanes in Domino Reactions. One-Step Enantioselective Synthesis of Pyrrolo[1,2-a]quinolines

• DOI: 10.1021/acs.orglett.6b00173
• Publication Date: 2016-02-26T14:03:35Z
• Authors: Eduardo Sanchez-Diez; Diana L. Vesga; Efraim Reyes; Uxue Uria; Luisa Carrillo; Jose L. Vicario
• Keywords: Iminium; Cyclopropane; Domino; Decarboxylation; Aldol reaction; Cascade reaction; Hydroamination

An easy and straightforward procedure has been developed for the synthesis of highly enantioenriched pyrrolo[1,2-a]quinolines through a one-pot process that comprises domino cyclopropane ring opening/aza-Michael/aldol reaction followed by acid-promoted lactamization. The key feature synthetic approach relies on ability conveniently functionalized cyclopropaneacetaldehydes to undergo organocatalytic activation chiral secondary amine enables catalytic generation donor–acceptor cyclopropane. This intermediate potential opening generates an electrophilic α,β-unsaturated iminium ion subsequently reacts already mentioned sequence in which stereochemical information is very efficiently transferred from catalyst final products. Moreover, one alkoxycarbonyl moieties can be easily removed standard hydrolysis/decarboxylation, providing access target adducts as single stereoisomers.