Schneider Heidi, Hock Andreas, Bertermann Rüdiger, Radius Udo
Institut für Anorganische Chemie, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany.
Chemistry. 2017 Sep 7;23(50):12387-12398. doi: 10.1002/chem.201702166. Epub 2017 Jul 21.
The synthesis of mono-NHC alane adducts of the type (NHC)⋅AlH (NHC=Me Im (1), Me Im (2), iPr Im (3 and [D ]-3), iPr Im (4), Dipp Im (10); Im=imidazolin-2-ylidene, Dipp=2,6-diisopropylphenyl) and (NHC)⋅AliBu H (NHC=iPr Im (11), Dipp Im (12)) as well as their reactivity towards different types of carbenes is presented. Although the mono-NHC adducts remained stable at elevated temperatures, ring expansion occurred when (iPr Im)⋅AlH (3) was treated with a second equivalent of the carbene iPr Im to give (iPr Im)⋅AlH(RER-iPr ImH ) (6). In 6, {(iPr Im}AlH} is inserted into the NHC ring. In contrast, ring opening was observed with the sterically more demanding Dipp Im with the formation of (iPr Im)⋅AlH (ROR-Dipp ImH )H Al⋅(iPr Im) (9). In 9, two {(iPr Im)⋅AlH } moieties stabilize the ring-opened Dipp Im. If two hydridic sites are blocked, the adducts are stable with respect to further ring expansion or ring opening, as exemplified by the adducts (iPr Im)⋅AliBu H (11) and (Dipp Im)⋅AliBu H (12). The adducts (NHC)⋅AlH and (iPr Im)⋅AliBu H reacted with cAAC by insertion of the carbene carbon atom into the Al-H bond to give (NHC)⋅AlH /iBu (cAAC H) (13-18) instead of ligand substitution, ring-expansion, or ring-opened products.
本文介绍了单-NHC铝烷加合物（NHC）⋅AlH（NHC = Me Im（1）、Me Im（2）、iPr Im（3和[D ]-3）、iPr Im（4）、Dipp Im（10）；Im = 咪唑啉-2-亚基，Dipp = 2,6-二异丙基苯基）和（NHC）⋅AliBu H（NHC = iPr Im（11）、Dipp Im（12））的合成及其对不同类型卡宾的反应活性。尽管单-NHC加合物在高温下保持稳定，但当用第二当量的卡宾iPr Im处理（iPr Im）⋅AlH（3）时会发生环扩张，生成（iPr Im）⋅AlH（RER-iPr ImH ）（6）。在6中，{(iPr Im}AlH}插入到NHC环中。相反，对于空间位阻更大的Dipp Im则观察到开环，生成（iPr Im）⋅AlH（ROR-Dipp ImH ）H Al⋅(iPr Im)（9）。在9中，两个{(iPr Im)⋅AlH }部分稳定了开环的Dipp Im。如果两个氢位点被阻断，加合物对于进一步的环扩张或开环是稳定的，如加合物（iPr Im）⋅AliBu H（11）和（Dipp Im）⋅AliBu H（12）所示。加合物（NHC）⋅AlH和（iPr Im）⋅AliBu H与cAAC反应，通过将卡宾碳原子插入Al-H键中生成（NHC）⋅AlH /iBu（cAAC H）（13 - 18），而不是配体取代、环扩张或开环产物。
