STRECKER Aminoacid synthesis

STRECKER Aminoacid synthesis Synthesis of a-amino acids from aldehydes or ketones via cyanohydnns... 

The presence of oe-hydroxycarboxylic acids together with a-aminoacids could lead to an estimate of the local concentration of ammonia when these molecules were synthesised. Such an estimation method implies the assumption that the syntheses of the two classes of molecules were simultaneous and started from the same organic substrate, i.e. aldehydes25 . From aldehydes, aminoacids can be obtained by the Strecker synthesis (aldehyde, HCN, NH3 in aqueous solution), while hydroxyacids can be synthesised from the cyanhydrin synthesis (aldehyde + HCN) followed by a hydrolysis. Nevertheless, it must be emphasised that all aminoacids detected in carbonaceous chondrites cannot be obtained by the Strecker synthesis. This remark limits the interest of the previous arguments concerning the concentration of NH3 during the accretion phase. 

Discovered in the middle of the 19th century, the Strecker reaction is one of the earliest atom-economic multicomponent reactions. Amino nitriles were simply obtained from ammonia, hydrogen cyanide and an aldehyde. These products are important intermediates for the synthesis of natural and unnatural a-aminoacids. Due to the ever-increased demand for enantioenri-chied a-aminoacids, the asymmetric Strecker reaction has emerged as a viable synthetic method. Since the first report published in 1996, the catalytic enantioselective cyanation of preformed imines was intensively studied and several excellent reviews were devoted to this topic. ... 

---