An elegant, asymmetric route to amino acid derivatives The aldol reaction is widely used for the production of carbonyl compounds. The importance of these building blocks, which comprise a wide variety of biologically relevant molecules, has encouraged the development of a new catalytic asymmetric method for their production. Industrial Technologies © Shutterstock Over the past decades, tremendous progress has been made in asymmetric synthesis. In particular, enolate chemistry has proven to be a powerful tool for building carbon-carbon, carbon-halogen, carbon-nitrogen and carbon-oxygen bonds in the synthesis of organic molecules. The aim of the EU-funded project ENANTIOMEAR (Enantioselective metal enolate alkylation reactions under cooperative Lewis base and hydrogen-bond donor) was to demonstrate difficult to achieve aldol reactions with unactivated ketones. Aldol reactions utilise enolate chemistry. For the promotion and effective control of these particular reactions, researchers have developed a binary catalyst system. This comprises metal ions, such as silver ions, and an amino-phosphine precatalyst at 2:1 ratio. The new catalyst system promotes the aldol reactions of isocyanoacetates with aldehydes as well as reactions of aldimines and ketimines with high diastereo and enantio control. The cinchona-derived precatalyst is equipped with Brønsted and Lewis basic sites. In combination with silver ions, these features prompted aldol reactions of isocyanoacetate esters with unactivated ketones to produce functionalised oxazolines. Subsequent hydrolytic manipulation of the oxazoline heterocycles lead to the production of amino acid derivatives possessing a tertiary alcohol. The methodology established within ENANTIOMEAR for the transformation of simple ketones into amino acid derivatives is of interest to pharmaceuticals and fine chemicals industries. The details are described in a publication in Angewandte Chemie International Edition. Keywords Amino acid derivatives, aldol reaction, catalytic asymmetric method, enolate chemistry, ENANTIOMEAR
