Synthesis of Vinyl Bromides Via Reaction of Vinyl Boronic Acids with Sodium Bromide

Vinyl halides have proven to be useful synthetic intermediates. 1,2 Recently, it was discovered that vinyl iodides are more stable to in-vivo deiodination than the corresponding alkyl iodides. 3,4 This fact makes the vinyl halides potentially valuable in the design and syntheses of radiopharmaceuticals. Because of our interest in pharmaceutical design, we recently developed a synthesis of vinyl iodides in which vinyl boronic acids are allowed to react with sodium iodide in the presence of mild oxidizing agents. 5 The method has been successfully applied to a variety of functionally substituted, physiologically active molecules including fatty acids and steroids. 6 We now wish to report that vinyl bromides are readily synthesized via the reaction of vinyl boronic acids with sodium bromide in the presence of mild oxidizing agents such as N-chlorosuccinimide.