Lanthanide Triflate-Promoted Palladium-Catalyzed Cyclization of Alkenyl β-Keto Esters and Amides
摘要:
graphicsLanthanide triflates were found to promote the palladium-catalyzed cyclization of alkenyl beta-keto esters and amides. In the presence of catalytic amounts of PdCl2(MeCN)(2) and Ln(OTf)(3), various alkenyl beta-keto esters and amides underwent regioselective cyclization reactions to give six-, seven-, or eight-membered-ring carbocycles in moderate to excellent yields.
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
esters are versatile intermediates for the synthesis of many biologically active natural products. Here we report a new intramolecular cyclopropanation reaction of unsaturated beta-keto esters. In the presence of I(2), Et(3)N, and Lewis acids such as Mg(ClO(4))(2) and Yb(OTf)(3), beta-keto esters 1 bearing various olefin substituents were transformed to fused cyclopropanes 2 in a highly stereospecific manner