Methodologies to synthesize compounds with attention to regio-, diastereo-, and enantiospecificity are essential. Enantioselective catalysis is a preferred method to produce enantiopure molecules from a small source of enantiopure material. Many of the most significant advances in this area have come with the development of new chiral ligands, which are continually being developed to improve known catalytic reactions and to promote previously unknown or unsuccessfully catalyzed organic reactions. While many organic reactions are catalyzed with high enantioselectivity, improvements are still required to (i) expand the set of reactions a complex can catalyze, (ii) expand the number of useful substrates that can be reacted with high enantioselectivity, (iii) tolerate a wider set of functional groups on the substrates, and (iv) decrease the cost of catalyst manufacturing. The ongoing design and synthesis of new chiral ligands continues to have a positive impact by reducing the extent of these problems. Herein we will discuss the general development of new ligands from the design concept to their application in enantioselective catalysis. After a general survey of the field, we will focus on the development of our C2-symmetric chiral mer-coordinating tridentate nitrogen donor ligand system, 1,3-bis(4,5-dihydrooxazol-2-ylimino)isoindolines. Details of their preparation from a two-step synthetic process incorporating an in-situ formation of the desired ligand in its deprotonated form bound to a metal center followed by the ligand’s isolation using a thiol-based ligand-displacement strategy will be presented. The latter step takes advantage of hard soft acid base (HSAB) theory to isolate the desired ligand in pure form with relative ease. Finally, we will conclude with the preliminary results of the use of our ligand system in metal-mediated enantioselective catalysis reactions.

Developing ligands for use in metal-mediated enantioselective catalysis

251st National Meeting (2016)

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