Enantioselective alpha-arylation of aldehydes via organo-SOMO catalysis. An ortho-selective arylation reaction based on an open-shell pathway.
The intramolecular alpha-arylation of aldehydes has been accomplished using singly occupied molecular orbital (SOMO) catalysis. Selective oxidation of chiral enamines (formed by the condensation of an aldehyde and a secondary amine catalyst) leads to the formation of a 3pi-electron radical species. These chiral SOMO-activated radical cations undergo enantioselective reaction with an array of pendent electron-rich aromatics and heterocycles thus efficiently providing cyclic alpha-aryl aldehyde products (10 examples: > or = 70% yield and > or = 90% ee). In accordance with our radical mechanism, when there is a choice between arylation at the ortho or para position of anisole substrates, we find that arylation proceeds selectively at the ortho position.
Conrad
Jay C
JC
Merck Center for Catalysis at Princeton University, Princeton, New Jersey 08544, USA.
Kong
Jongrock
J
Laforteza
Brian N
BN
MacMillan
David W C
DW
D000447:Aldehydes / Q000737:chemistry*; D002384:Catalysis; D007212:Indolizines / Q000138:chemical synthesis / Q000737:chemistry; D013237:Stereoisomerism; D013379:Substrate Specificity
D000447:Aldehydes; D007212:Indolizines; C512155:tashiromine