Catalytic Boration of Alkyl Halides with Borane without Hydrodehalogenation Enabled by Titanium Catalyst
作者:Xianjin Wang、Penglei Cui、Chungu Xia、Lipeng Wu
DOI:10.1002/anie.202100569
日期:2021.5.25
titanium‐catalyzed boration of alkyl (pseudo)halides (alkyl‐X, X=I, Br, Cl, OMs) with borane (HBpin, HBcat) is reported. The use of titanium catalyst can successfully suppress the undesired hydrodehalogenation products that prevail using other transition‐metal catalysts. A series of synthetically useful alkyl boronate esters are readily obtained from various (primary, secondary, and tertiary) alkyl electrophiles,
and tertiary unactivated alkyl halides as alkyl radical precursors and the use of a simple catalyst system are the highlights of this reactivity manifold. The reactions exhibit wide scope, occur under mild conditions, and furnish the products in excellent yields.
AbstractA transition‐metal‐free intermolecular coupling reaction of halocompounds with styrenes in the presence of NaH and 1,10‐phenanthroline was developed. This reaction afforded hydrocarbonated products with complete anti‐Markovnikov selectivity. The method allows the use of a wide range of halocompounds, including aryl and alkyl halides, and good functional group tolerance. Detailed mechanistic studies indicated that an anilide anion generated in situ by the NaH‐mediated reduction of 1,10‐phenanthroline works as an electron donor and a hydrogen source.