Preparation of <i>β</i>-Keto Esters and <i>β</i>-Diketones by C-Acylation/Deacetylation of Acetoacetic Esters and Acetonyl Ketones with 1-Acylbenzotriazoles
作者:Alan R. Katritzky、Zuoquan Wang、Mingyi Wang、Chavon R. Wilkerson、C. Dennis Hall、Novruz G. Akhmedov
DOI:10.1021/jo049274l
日期:2004.10.1
Acyl-, aroyl-, and heteroaroyl-acetic esters 6a−f and 8a−l are prepared by reactions of 1-acylbenzotriazoles 1a−k with acetoacetic esters 5 or 7a,b in the presence of sodium hydride followed by regioselective deacetylation. Similar C-acylation/deacetylation of acetylacetone and benzoylacetone affords β-diketones 10a−d and 13a−c, respectively.
The reaction of Baylis-Hillman adducts with iodobenzenes using commercially available palladium-on-carbon as a catalyst under solvent-free conditions afforded the corresponding coupling products, alpha-benzyl-beta-keto esters, in high to excellent yields. The reactions are very efficient.
Enantioselective and Diastereoselective Ir-Catalyzed Hydrogenation of α-Substituted β-Ketoesters via Dynamic Kinetic Resolution
An iridium/f-amphol catalytic system for the enantioselective hydrogenation of α-substituted β-ketoesters via dynamic kinetic resolution is reported. The desired anti products were obtained in high yields (up to 98%) with good diastereoselectivity (up to 96:4 diastereometic ratio (dr)) and excellent enantioselectivity (up to >99% enantiomeric excess (ee)). A catalytic model is proposed to explain the