Intramolecular Asymmetric α-Allylation of Aldehydes via SOMO Umpolung

Significance

The authors expand SOMO catalysis to the intramolecular α-allylation of aldehydes using a secondary amine catalyst. Under the oxidative reaction conditions [using >2 equiv of ceric ammonium nitrate (CAN)], aldehyde-tethered allylsilanes could be converted into the desired cyclic compounds with good yield and enantioselecti­vity. Addition of water (2 equiv) could increase chemical yield and diastereoselectivity, however, not the enantioselectivity (see more mechanistic details: Angew. Chem. Int. Ed. 2010, 49, 6106). The presented methodology can be utilized to construct five- and six-membered cyclic compounds with aldehyde and olefin functionalities.