Synthsis of new chiral norbornadiene bis(Oxazoline) compounds

In recent years, C2-symmetric bis(oxazoline) ligands have been proven to be effective chiral ligands as they perform a variety of asymmetric transformations. In this study, it was aimed to synthesize rigid, bicyclic, norbornadien bis(oxazoline) ligands 55a ? d and 56 which can be synthesized rather easily in several steps and form seven-membered metal-chelate. To achieve the synthesis of these ligands 2,3-dicarbometoksinorbonadiene 57 was chosen as the starting molecule. This compound was hydrolyzed and then chlorinated to obtain diacyl chloride 58. Diacyl chloride 58 was reacted with chiral ß-amino alcohols 63a-d and 64 to give bis(hydroxyamides) 59a-d and 60; cyclization of these amides resulted in the synthesis of the targeted bis(oxazoline) ligands 55a ? d and 56 with 35-85% yields.