Regio- and stereoselective synthesis of functionalized allylic fluorides via palladium-catalyzed three-component tandem carbofluorination of allenes

摘要

We developed a highly efficient palladium-catalyzed three-component tandem carbofluorination of allenes with An and AgF. Nucleophilic trapping of pi-allyl palladium intermediates generated from carbopalladation of allenes with AgF delivers functionalized allylic fluorides with highly branched selectivity. This transformation features simultaneous construction of C-C and C-F bond in one step, allowing for the facile synthesis of functionalized allylic fluorides, valuable synthetic building blocks. Moreover, a good correlation between regioselectivity and substituent Hammett constants was observed in the reactions of mono-alkyl substituted allene substrates, corroborating with the proposed outer-sphere fluorination pathway. This study uncovered the regioselectivity trends being controlled by both electronic and steric factors, which paved the way for further developments in selective synthesis of branched functionalized allylic fluorides difficult to access from established methodologies. (C) 2015 Elsevier Ltd. All rights reserved.