Pd(OAc)2-Catalyzed Carbonylation of Amines
| Autor: | Takatoshi Nakamura, Hideo Nagasaki, Mamoru Miyazawa, Masao Tokuda, Motoki Yuguchi, Tetsuro Yamazaki, Kazuhiko Orito, Satoshi Yamashita, Akiyoshi Horibata, Harumi Ushito |
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| Rok vydání: | 2006 |
| Předmět: | |
| Zdroj: | The Journal of Organic Chemistry. 71:5951-5958 |
| ISSN: | 1520-6904 0022-3263 |
| DOI: | 10.1021/jo060612n |
| Popis: | A phosphine-free catalytic system [Pd(OAc)2-Cu(OAc)2-air] induced a substrate-specific carbonylation of amines in boiling toluene under CO gas (1 atm). Symmetrical N,N'-dialkylureas were obtained by the carbonylation of primary amines. N,N,N'-Trialkylureas were selectively formed by addition of a secondary amine to the above reaction vessel. Secondary amines did not give tetraalkylureas. However, dialkylamines with a phenyl group on their alkyl chains, such as N-monoalkylated benzylic amine or phenethylamine derivatives, underwent a direct aromatic carbonylation to afford five- or six-membered benzolactams. In the carbonylation, the chelation effect or steric repulsion between Pd(II) and the meta-substituent in the ortho-palladation and the ring sizes of cyclopalladation products that were formed prior to carbonylation were found to generate good site selectivity and increase the reaction rate. In contrast, carbonylation of omega-arylalkylamines with a hydroxyl group gave neither ureas nor benzolactams but instead produced 1,3-oxazolidinones smoothly. Hydrochlorides of amines also underwent carbonylation to afford the corresponding amides under the conditions used. This procedure made it possible to prepare ureas of amino acid esters and N-alkylcarbamates in practical yields. |
| Databáze: | OpenAIRE |
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