Diamidophosphites with isomeric carborane fragments: a comparison of catalytic activity in asymmetric Pd-catalyzed allylic substitution reactions

New chiral diamidophosphite ligands containing electron-donating 9-meta-carborane and electron-withdrawing I-meta-carborane substituents have been synthesized. The ligand 3a with an electron-donating group demonstrated high enantioselectivity in Pd-catalyzed allylic substitution reactions with C-, S- and N-nucleophiles (up to 98% ee). The isomeric diamidophosphite 3b bearing an electron-withdrawing substituent showed in all cases, moderate-to-poor conversion and lower enantioselectivity. (C) 2010 Elsevier Ltd. All rights reserved.