Iron-Catalyzed, Highly Regioselective Synthesis of α-Aryl Carboxylic Acids from Styrene Derivatives and CO<sub>2</sub>
Mark D. GreenhalghSchool of Chemistry, University of Bristol, Cantock’s Close, Bristol,
BS8 1TS, United KingdomStephen P. ThomasSchool of Chemistry, University of Bristol, Cantock’s Close, Bristol,
BS8 1TS, United Kingdom
2012en
ABI
Abstract
The iron-catalyzed hydrocarboxylation of aryl alkenes has been developed using a highly active bench-stable iron(II) precatalyst to give α-aryl carboxylic acids in excellent yields and with near-perfect regioselectivity. Using just 1 mol % FeCl(2), bis(imino)pyridine 6 (1 mol %), CO(2) (atmospheric pressure), and a hydride source (EtMgBr, 1.2 equiv), a range of sterically and electronically differentiated aryl alkenes were transformed to the corresponding α-aryl carboxylic acids (up to 96% isolated yield). The catalyst was found to be equally active with a loading of 0.1 mol %. Preliminary mechanistic investigations show that an iron-catalyzed hydrometalation is followed by transmetalation and reaction with the electrophile (CO(2)).
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