Mild Two-Step Process for the Transition-Metal-Free Synthesis of Carbon-Carbon Bonds from Allylic Alcohols/Ethers and Grignard Reagents

摘要

In contrast to the immense amount of effort devoted to developing transition-metal-mediated allylic substitution reactions with soft nucleophiles (the Tsuji-Trost reaction), far fewer methods exist for allylic substitution reactions utilizing hard nucleophiles such as Grignard reagents. Substitution reactions with Grignard nucleophiles are predominantly catalyzed by Cu(I) salts, although variants promoted by other transition metals are also known. Uncatalyzed reactions with Grignard reagents are rare and suffer from problems such as poor yields and regioselectivities. In recent years, there has been an intense push toward developing chemistry that is more environmentally benign. A part of this larger goal is a reduction in the use of transition metals, which can sometimes be toxic, expensive, or difficult to properly dispose of in large quantities. Herein we report a mild two-step procedure for the regioselective, transition-metal-free allylic substitution reaction between Grignard reagents and phosphorothioate esters prepared from the corresponding allylic alcohols and ethers.