Iron-Catalyzed 1,4-Hydroboration of 1,3-Dienes

摘要

Iron can adopt formal oxidation states ranging from -II to +VI. Iron complexes are used as catalysts in synthetic chemistry for carbon-heteroatom and carbon-carbon bond-forming reactions. Low-valent iron complexes can catalyze cross-coupling, cycloisomerization, and cycloaddition reactions. We are interested in iron catalysis for the identification of useful, previously inaccessible reaction chemistry and report here C-B bond formation by hydroboration of 1,3-dienes. To our knowledge, there are no other examples of Fe-catalyzed hydroboration reactions of olefinic substrates. The allylborane products are formed regio- and stereo-selectively with (E)-double bond geometry exclusively and are challenging to access selectively with conventional chemistry.