SYNTHESIS OF NEW CHIRAL BRONSTED ACIDS

The electrophilic activation of a substrate by means of a Brønsted acid is, undoubtedly, the most straightforward and common approach used to promote a reaction and hence Brønsted acids have been widely utilized as efficient catalysts for numerous organic transformations. Despite that, the synthetic utility of a Brønsted acid as a catalyst for stereoselective reactions has been quite limited until recently; however in the last decade chiral organic Brønsted acid catalysts, initially developed by Akiyama(1) and Terada(2), have been successfully used as promoters of a wide class of transformations. At the present organic Brønsted acid catalysts are almost exclusively based on the non-natural BINOL chiral scaffold; only one example of TADDOL-derived Brønsted acid catalyst exists: the scarcely active TADDOP. Our aim is to synthetize a new class of catalysts based on tartaric acid as cheap chiral scaffold. The catalysts will be tested in some model stereoselective organocatalyzed reactions such as: reductions with Hantzsch ester of ketoimines, addition of several nucleophiles to imines, hydrophosphonylation reactions, aza-Diels-Alder cycloadditions, Friedel-Creaft reactions and many others.(3) References: 1. Akiyama, T.; Itoh, J.; Yokota, K.; Fuchibe, K. Angew. Chem. Int. Ed. 2004, 43, 1566-1568. 2. Terada, M.; Uraguchi, D. J. Am. Chem. Soc. 2004, 126, 5356-5357. 3. Rueping, M.; Nachtsheim, B. J.; Ieawsuwan, W.; Atodiresei, I. Angew. Chem. Int. Ed. 2011, 50, 6706-6720.