Development of new P-chiral phosphorodiamidite ligands having a pyrrolo[1,2-c]diazaphosphol-1-one unit and their application to regio- and enantioselective iridium-catalyzed allylic etherification

Ten types of new P-chiral phosphorodiamidite ligands having pyrrolo[1,2-c][1,3,2]diazaphosphol-1-one backbone were designed and prepared. They were preliminarily utilized for iridium-catalyzed asymmetric allylic etherification of cinnamyl carbonate with phenol, where both R- and S-products were obtained with good enantioselectivity (up to 74% ee) by changing the N- and P-substituents of the ligands. The opposite enantioselectivity in iridium-catalyzed allylic substitution was explained by DFT calculations of the energy difference of the pi-allyliridium-phosphorodiamidite intermediates.