Axially chiral 1,1'-binaphthyl-2-carboxylic acids are little explored ligands in asymmetric catalysis. An in situ generated titanium-carboxylate complex Ti(OiPr)4–H2O–MeO-BINA-Cox catalyzes the intramolecular asymmetric hydroalkoxylation of non-activated alkenes at unusually high temperature for asymmetric catalysis ("HOT-CAT"). The scarcity of reported structural variations poses serious limitations to the further development of this new asymmetric catalysis. Our work was focused on exploring a variety of synthetic strategies for introducing core structure variations at different positions of the molecule. As a result, we can present more than 30 chiral biaryl-carboxylic acids, which have been evaluated in the above-mentioned model reaction. The results will be presented together with further substrate scope extension studies and insights into the nature of the catalyst system. Furthermore, we also systematically improved the five-step-synthesis of the MeO-BINA-Cox core structure due to the uncertain scalability of the procedures reported in the literature.

Synthesis of axially chiral biaryl-carboxylic acids (BINA-Cox) and their evaluation as ligands in asymmetric titanium-catalyzed hydroalkoxylation

2019 Fall National Meeting

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