Chen Chaohuang, Daniliuc Constantin G, Kehr Gerald, Erker Gerhard
Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster, Corrensstraße 40, 48149 Münster, Germany.
J Am Chem Soc. 2021 Dec 22;143(50):21312-21320. doi: 10.1021/jacs.1c09774. Epub 2021 Dec 11.
Deprotonation of [(NHC)(Fmes)B-allyl] borenium cations (NHC, IMes () or IMe (); Fmes, 2,4,6-(CF)CH) provides an easy entry to the NHC-stabilized 1-bora-1,3-butadienes. They feature a planar s-trans-conformation just like 1,3-butadiene. The 1-borabutadiene undergoes hydroboration reactions; the HB(CF) hydroboration product is trapped with CO or an isonitrile to give the respective cyclic zwitterionic borenium-borate enolate or enamide products. 1-Borabutadiene undergoes 1,4-chalcogenation with elemental sulfur or selenium, and it gives the six-membered heterocyclic 1,4-addition product with the S═O bond of sulfur dioxide. Compound served as a precursor for the formation of a borylated η-allyl ligand at Ru. formed a Rh complex by reaction with [Rh(ethylene)Cl]. It subsequently underwent an intramolecular C-H activation reaction to a mixture of η-methyl-boraallyl Rh complex isomers.
[（NHC）（Fmes）B-烯丙基]硼正离子（NHC为IMes（）或IMe（）；Fmes为2,4,6-（CF）CH）的去质子化反应为制备NHC稳定的1-硼杂-1,3-丁二烯提供了一条简便途径。它们具有与1,3-丁二烯类似的平面s-反式构象。1-硼杂丁二烯会发生硼氢化反应；HB（CF）硼氢化产物会被CO或异腈捕获，生成相应的环状两性离子硼正离子-硼酸酯烯醇盐或烯酰胺产物。1-硼杂丁二烯与元素硫或硒发生1,4-硫属化反应，并与二氧化硫的S═O键生成六元杂环1,4-加成产物。化合物用作在Ru上形成硼化η-烯丙基配体的前体。通过与[Rh（乙烯）Cl]反应形成Rh配合物。随后它发生分子内C-H活化反应，生成η-甲基-硼杂烯丙基Rh配合物异构体的混合物。
