Catalytic Use of Indium(0) for Carbon-Carbon Bond Transformations in Water: General Catalytic Allylations of Ketones with Allylboronates

摘要

Innovative catalysis for effective C-C bond transformations in water is an exciting challenge in organic synthesis. During our studies toward environmentally benign catalyst systems in water, we have recently become interested in In(0), a nontoxic, inexpensive, and water-compatible main group metal. While organoindium reagents are known to tolerate various functional groups, more than a stoichiometric amount of In metal is typically required in synthesis. To the best of our knowledge, the catalytic use of In(0) for C-C bond formation is unknown.rnRecently, remarkable advances in catalytic allylations of ketones have been achieved using stannanes, silanes, boron reagents, and in situ prepared manganese compounds in combination with various catalysts. Unfortunately, these reactions rely on strictly anhydrous conditions and/ or on the use of more than 1 equiv of corrosive and/or toxic allylation agents. Moreover, with only a single exception, the substrate scope is limited. Clearly, with respect to safety and environmental concerns, development of general catalytic allylations of ketones in water is of central importance. In earlier reports, we have disclosed indium(I) iodide catalyzed allylations of ketones and acylhydrazones with allylboronates. However, this low oxidation state catalyst readily decomposes in water (redox-disproportionation; see Supporting Information (SI)). We report here the unprecedented catalytic use of In(0) for general catalytic C-C bond transformations in water.