Pd(0)-based synthetic approaches to 1,1-disubstituted-3,4-dimethylenecyclopentanes as intermediates in the preparation of a,a-disubstituted amino acid derivatives possessing indane and diazaindane skeletons

A comparison is established between ethyl nitroacetate and ethyl N(diphenylmelhylene)glycinate as anionic glycine equivalents for the preparation of bicyclic or tricyclic a.adisubstituted amino acids. Palladiummediated approaches to 1.1disubstituted-3,4-di méthylène cyclopentanes are presented (intramolecular reductive coupling of 2.6-dibromol.6dienes and cycloisomerization of 1.6enynes). © Springer-Verlag Ibérica 1997.