A Synthesis of Substituted α-Allenols via Iron-Catalyzed Cross-Coupling of Propargyl Carboxylates with Grignard Reagents

alpha-Allenols are attractive and versatile compounds whose preparation can be a nontrivial task. In this Letter, we provide a method for the prompt synthesis of substituted alpha-allenols via a catalytic cross-coupling reaction which makes use of a nontoxic and cost-effective iron catalyst. The catalyst loading is typically as low as 1-5 mol %. The mild reaction conditions (-20 degrees C) and the short reaction time (15 min) allow for the presence of a variety of functional groups. Moreover, the reaction was shown to be scalable up to gram scale and the propargyl substrates are readily accessible by a one-pot synthesis.