Synthesis of Optically Active Ferrocene Analogues of Salicylic Acid Derivatives and Rhodium(II)-Catalyzed Asymmetric Intramolecular C–H Insertion of α-Diazo β-Keto Esters Using New Chiral Carboxylato Ligands

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Abstract
The ferrocene analogue of salicylic acid, 2-hydroxyferrocenecarboxylic acid was synthesized via monolithiation of ferrocene with t-butyllithium, and resolved to optically active forms. Optically active 2-hydroxyferrocenecarboxylic acid was converted to 1-hydroxyferrocenecarbaldehyde, ferrocene analogue of salicylaldehyde, and 2-alkoxyferrocenecarboxylic acids. The later compounds were used as chiral carboxylato ligands for the rhodium(II)-catalyzed asymmetric intramolecular C–H insertion of α-diazo β-keto esters (up to 42% ee).