Transition Metal-Catalyzed, Chlorine-Transfer Radical Cyclizations of 2-(3-Alken-1-oxy)-2-Chloroacetates. Formal Total Synthesis of Avenaciolide and Isoavenaciolide
作者:Jan H. Udding、Kees C. J. M. Tuijp、Marco N. A. van Zanden、Henk Hiemstra、W. Nico Speckamp
DOI:10.1021/jo00087a011
日期:1994.4
A novel method for the synthesis of functionalized tetrahydrofurans is described. This method involves the treatment of 2-(3-alken-1-oxy)-2-chloroacetates 1 with a catalytic amount of Cu(bpy)Cl in refluxing 1,2-dichloroethane to give good yields of 3-(1-chloroalkyl)-2-tetrahydrofuran carboxylic esters 2. The stereochemical course of the radical cyclizations shows a-preference for the formation of 2,3-cis-substituted tetrahydrofurans in all cases. This selectivity is exploited in the formation of bicyclic lactones which form spontaneously upon ester hydrolysis. As an application of this methodology a formal total synthesis of avenaciolide (28) and isoavenaciolide (29) is described.