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DOI: 10.1055/s-0032-1316565
Carbonylative Cyclization of o-Halobenzoic Acids for Synthesis of N-Substituted Phthalimides Using Polymer-Supported Palladium–N-Heterocyclic Carbene as an Efficient, Heterogeneous, and Reusable Catalyst
Publication History
Received: 13 March 2012
Accepted after revision: 01 June 2012
Publication Date:
29 June 2012 (online)


Abstract
The carbonylative cyclization of o-iodobenzoic acid with a variety of primary amines and carbon monoxide (1 bar) using a polymer-supported palladium–N-heterocyclic carbene complex (PS-Pd-NHC) as the catalyst gives N-substituted 1H-isoindole-1,3(2H)-diones (phthalimides) in good to excellent yields with a short reaction time. The catalyst is efficient, heterogeneous, and phosphine-free, it exhibited remarkable activity and it is also recyclable (4 consecutive cycles). The use of methyl o-iodobenzoate as the substrate under these conditions also gave N-substituted 1H-isoindole-1,3(2H)-diones, but with lower yields. Cyclization of o-iodobenzyl alcohol with carbon monoxide under these conditions gave isobenzofuran-1(3H)-one (phthalide).
Key words
carbonylative cyclization - heterogeneous catalysis - N-heterocyclic carbene - phosphine-free - phthalimides - isoindolesSupporting Information
- for this article is available online at http://www.thieme-connect.com/ejournals/toc/synthesis.
- Supporting Information