Doubly activated cyclopropanes as synthetic precursors for the preparation of 4-nitro- and 4-cyano-dihydropyrroles and pyrroles

Org Lett. 2005 Jun 9;7(12):2313-6. doi: 10.1021/ol050442l.

Abstract

[reaction: see text] 1-Nitro- and 1-cyano-cyclopropyl ketones have been prepared in an expedient manner from cyclopropanation reactions of alkenes by diazo compounds or in situ-generated phenyliodonium ylides catalyzed by Rh(II) carboxylates. The doubly activated cyclopropanes were used as synthetic precursors for the regiospecific synthesis of 4-nitro- and 4-cyano-dihydropyrroles upon treatment with primary amines. Oxidation of the dihydropyrroles with DDQ allows rapid access to densely functionalized pyrroles.