During the course of synthetic studies on the 5, 6-disubsituted 4-oxo-tetrahydro-2-pyroneskeleton in connection with biologically active compounds, we have found a convenient procedure for the regioselective introduction of a double bond in methyl alkyl ketones and a novel synthetic method for indan derivatives.
Palladium-Catalyzed Intramolecular Hydroalkylation of Alkenyl- ?-Keto Esters, ?-Aryl Ketones, and Alkyl Ketones in the Presence of Me3SiCl or HCl
作者:Xiaoqing Han、Xiang Wang、Tao Pei、Ross A. Widenhoefer
DOI:10.1002/chem.200400459
日期:2004.12.17
palladium-catalyzed hydroalkylation, but rather served as a source of HCl, which presumably catalyzes enolization of the ketone. Identification of HCl as the active promoter of palladium-catalyzed hydroalkylation led to the development of an effective protocol for the hydroalkylation of alkyl 3-butenyl ketones that employed sub-stoichiometric amounts of 2, HCl, and CuCl2 in a sealed tube at 70 degrees C.
Asymmetric syntheses of the enantiomerically pure trifunctional (R)-3-hydroxyesters (7)–(10) can be achieved by baker'syeastreduction of the hydrolysed β-keto carboxylates (2)–(5) instead of by reduction of the corresponding ester.
Reactivite des acylaldocetenes dans la cycloaddition intramoleculaire
作者:F. Leyendecker
DOI:10.1016/0040-4020(76)80048-8
日期:1976.1
The reactivity of acylaldoketenes, short-lived species generated by flash thermolysis of ϵ-ethylenic β-ketoesters, in [2 + 2] intramolecular cycloaddition reactions, has been examined. The observed regiospecificity can be rationalized by frontier orbital theory.
Et<sub>2</sub>AlCl-Promoted Asymmetric Phenylseleno Group Transfer Radical Cyclization Reactions of Unsaturated β-Hydroxy Esters
作者:Dan Yang、Qiang Gao、Bao-Fu Zheng、Nian-Yong Zhu
DOI:10.1021/jo048322z
日期:2004.12.1
unsaturated α-phenylseleno β-hydroxy esters underwent radical cyclization in the presence of Et2AlCl in benzene with sunlamp irradiation at 25−30 °C to give mono- and bicyclic group-transferred products in an efficient and highly regioselective and diastereoselective manner. To rationalize the high diastereoselectivities observed in this reaction, we propose a model based on chelation control of the