New preparative methods for allylic boronates and their application in stereoselective catalytic allylborations

Stereocontrolled additions of allylic metal reagents to carbonyl compounds constitute one of the most useful classes of transformations in organic synthesis. The recent development of Lewis and Bronsted acid-catalyzed manifolds for the allylboration of carbonyl compounds has opened doors toward an ideal carbonyl allylation methodology using stable and nontoxic allylic boronates as reagents. This paper describes the development of acid-catalyzed allylborations, mechanistic investigations of these new processes, and ongoing efforts toward general catalytic enantioselective allylboration methodologies. The preparation of optically enriched a-substituted allylic boronate reagents is discussed, as well as their applications in Lewis acid-catalyzed additions to afford skeletally diverse products like propionate units, polysubstituted furans, vinylcyclopropanes, and larger ring systems.