Synthesis of chiral P,N-ligands derived from quinoline and their application in asymmetric allylic alkylations

摘要

Chiral P,N-ligands derived from quinoline and with a trans and cis cyclohexane backbone were easily synthesised in four steps from quinoline N-oxide. The enantiopure trans isomer was obtained by the way of chiral resolution of the mixture of trans- and cis-2-(quinolin-2-yl)cyclohexanol with dibenzoyltartaric acid and then subjected to a Mitsunobu reaction and deprotection to give the corresponding cis isomer. The optical pure trans and cis isomer reacted with chlorodiphenylphosphine or PAr_2NEt _2 to obtain trans and cis P,N-ligands, which were used in asymmetric allylic alkylations with up to 78% ee and 84% ee respectively.