Synthesis of 9,9′-biphenanthryl-10,10′-bis(oxazoline)s and their preliminary evaluations in the Friedel–Crafts alkylations of indoles with nitroalkenes

Chiral 9,9′-biphenanthryl-10,10′-bis(oxazoline)s 6a–d were firstly prepared. These new chiral compounds were evaluated as ligands for the Friedel–Crafts alkylations of indoles with nitroalkenes, excellent yields and modest to good enantioselectivities were achieved.