α-(Aminomethyl)acrylates as acceptors in radical-polar crossover 1,4-additions of dialkylzincs: insights into enolate formation and trapping.

ABSTRACT: We demonstrate that α-(aminomethyl)acrylates are suitable acceptors for 1,4-additions of dialkylzincs in aerobic conditions. The air-promoted radical-polar crossover process involves the 1,4-addition of an alkyl radical followed by homolytic substitution at the zinc atom of dialkylzinc. Coordination of the nitrogen atom to zinc enables this S_H2 process which represents a rare example of alkylzinc-group transfer to a tertiary α-carbonyl radical. The zinc enolate thus formed readily undergoes β-fragmentation unless it is trapped by electrophiles in situ. Enolates of substrates having free N-H bonds undergo protodemetalation to provide ultimately the 1,4-addition adduct. In the presence of carbonyl acceptors, aldol condensation occurs providing overall a tandem 1,4-addition-aldol p

SUBMITTER: Palillero-Cisneros A 

PROVIDER: S-EPMC10520473 | biostudies-literature | 2023

REPOSITORIES: biostudies-literature