Axial Chirality around N–P Bonds Induced by Complexation between E(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub> (E = B, Al) and an <i>N</i>-Phosphine Oxide-Substituted Imidazolinylidene: A Key Intermediate in the Catalytic Phosphinoylation of CO<sub>2</sub>
作者:Takahiro Asada、Yoichi Hoshimoto、Takahiro Kawakita、Takuya Kinoshita、Sensuke Ogoshi
DOI:10.1021/acs.joc.9b03210
日期:2020.11.20
confirmed that this axial chirality arises from the restricted rotation around the N–P bond, caused by the steric repulsion between the C5–H atoms of the imidazolinylidene ring and the C6F5 rings on the B(C6F5)3 unit. Conversely, this axial chirality was not certainly observed via the complexation between SPoxIm and Al(C6F5)3. The carbene carbon atoms in (κ-O-SPoxIm)E(C6F5)3 (E = B, Al) remain sufficiently
围绕N-P键络合诱导的轴手性发生在所述的主要协调Ñ膦酰基组中的Ñ -氧化膦取代的imidazolinylidene(SPoxIm)到B(C 6 ˚F 5)3。(κ-O- SPoxIm)B(C 6 F 5)3的(R a)和(S a)阻转异构体在单晶晶格和优化的气相结构中独立观察到。实验和理论研究证实,这种轴向手性是由于咪唑啉基亚烷基环的C5–H原子与B(C 6 F)上的C 6 F 5环之间的空间排斥而导致的围绕N–P键的受限旋转引起的5)3个单元。相反,通过SPoxIm与Al(C 6 F 5)3之间的络合不能确定地观察到这种轴向手性。(κ-O- SPoxIm)E(C 6 F 5)3中的卡宾碳原子(E = B,Al)保持足够的亲核性以与CO 2反应,并且在存在催化量的Al(C 6 F 5)3的情况下,用SPoxIm进行的CO 2的膦酰基化反应比在没有Al的情况下进行得更快。(C 6 F 5)3。