Enantioselective organocatalysis using SOMO activation

The increasing demand for enantiomerically pure compounds of pharmaceutical importance has led to the development of several asymmetric approaches including the use of organocatalysts and other different activation modes. However, despite these advances, asymmetric -addition of an alkyl or aryl group to a ketone or aldehyde remains problematic. With this in mind, the current report focuses on the mechanism of singly occupied molecular (SOMO) activation using a chiral amine as catalyst and aldehyde as substrate. Figure 1A shows the transformation of the aldehyde and catalyst to an enamine and its oxidation to an activated SOMO cation intermediate. Using density functional theory (DFT) calculations first to prove the basis of stereoselectivity (Fig. 1B), the authors proceeded to perform the -allylation of different aldehydes (Table 1) forming products with yields that range from 70% to 88% and enantiomeric purity of 87% ee to 95% ee.