(Z)- and (E)-2-phenyl-4-benzylidene-5(4H)-oxazolones as dienophiles. Improved selectivity by the use of heterogeneous catalysts
作者:Carlos Cativiela、José I. García、José A. Mayoral、Elisabet Pires、Robert Brown
DOI:10.1016/0040-4020(95)00526-e
日期:1995.8
cyclopentadiene wth 1b the endo(2b)/exo(3b) selectivity is reversed as a function of the catalyst. Thus, in the reactions catalyzed by silicagel, alumina and exchanged clays, endo (2b) is the major product However, the exo cycloadduct (3b) is preferably obtained for reactions catalyzed by silicagel and alumina treated with TiCl4 and ZnCl2 supported on silicagel.