Palladium-Catalyzed Carbonylation Of C-H Bonds Of Anilines, And Enamides

Carbonylation reaction has become one of the most active areas of research in synthetic organic chemistry. In the past four decades, great progress has been made in transition-metal-catalyzed carbonylation and gained plentiful fruits. Carbonylation reaction provides a simple and effective strategy approach to the carbonyl compounds. The progress in carbonylation chemistry has been achieved in both academic laboratories and industry. Since seminal work by Heck and co-workers developed the carbonylation of aryl halides in 1974. After several years, a breakthrough in this area was made with the Pd-catalyzed carbonylation of aromatic C-H bonds by Fujiwara. Most of C-H bond carbonylation reactionds employ carbon monoxide which is an inexpensive and readily available Cl source. The first chapter will review the research work of Pd, Rh, Ru and Co-catalyzed C-H bond carbonylation reactions with CO in recent years.The second chapter will introduce palladium-catalyzed N-alkyl directed regioselective carbonylation of C-H bonds of N-alkyl anilines for synthesis of isatoic anhydrides under mild conditions. This novel Pd-catalyzed carbonylation reaction tolerates a wide range of functional groups and is a reliable method for the rapid elaboration of readily available N-alkyl anilines into a variety of substituted isatoic anhydrides. An important dimmer palladium intermediate in the stoichiometric reaction of Pd(OAc)2 with N-methylaniline was isolated and well characterized.The third chapter will introduce palladium-catalyzed oxidative carbonylation of aromatic C-H bonds of N-alkylanilines with CO and alcohols for the synthesis of o-aminobenzoates. Various aliphatic alcohols and phenol were tolerated in the reaction to afford the corresponding o-aminobenzoates. To demonstrate the synthetic utility of this reaction which was successfully performed on a 1.0 mmol scale to afford o-aminobenzoate in slightly lower yield. In addition, the benzyl group can be easily removed under reductive condition with Pd/C as catalyst to afforded N-H o-aminobenzoate.The forth chapter will introduce palladium-catalyzed oxidative carbonylation of the alkenyl C-H bonds of enamides:synthesis of 1,3-oxazin-6-ones. The reaction employs KI and Ac2O as additives not only proceeded smoothly to produce the desired carbonylation products, but also inhibiting the decomposition of enamides. An important vinylpalladium intermediate was characterized by 1H NMR and high-resolution mass spectroscopy. This vinylpalladium intermediate provides an evidence for the alkene C-H bond activation and carbonyltion.