Lapshin Ivan V, Yurova Olga S, Basalov Ivan V, Rad'kov Vasily Yu, Musina Elvira I, Cherkasov Anton V, Fukin Georgy K, Karasik Andrei A, Trifonov Alexander A
G. A. Razuvaev Institute of Organometallic Chemistry of Russian Academy of Sciences , 49 Tropinina str. , 603137 Nizhny Novgorod , GSP-445, Russia.
A. E. Arbuzov Institute of Organic and Physical Chemistry, Kazan Scientific Center, Russian Academy of Sciences , 8 Academician Arbuzov str. , 420088 Kazan , Russia.
Inorg Chem. 2018 Mar 5;57(5):2942-2952. doi: 10.1021/acs.inorgchem.8b00088. Epub 2018 Feb 14.
A series of amido Ca and Yb(II) complexes LMN(SiMe) (1Yb, 1-4Ca) coordinated by amidine-amidopyridinate ligands L were synthesized via a transamination reaction between proligands LH and bisamido complexes MN(SiMe) (M = Yb, Ca). The reactions of YbN(SiMe) with proligands LH-LH containing CF and CHF fragments do not allow for preparing the target Yb(II) complexes, while the Ca analogues were synthesized in good yields. Complexes 1Yb and 1-4Ca were evaluated as precatalysts for hydrophosphination of styrene, p-substituted styrenes, α-Me-styrene, and 2,3-dimethylbutadiene with various primary and secondary phosphines (PhPH, 2,4,6-MeCHPH, 2-CNHPH, PhPH, CyPH). Complexes 1Yb, 1-4Ca performed high catalytic activities in styrene hydrophosphination with PhPH and PhPH and demonstrated high regioselectivity affording exclusively the anti-Markovnikov addition products. For primary PhPH the reactions (1:1 molar ratio of substrates) catalyzed by 1Yb, 1Ca, and 2Ca proved to be highly chemoselective affording the secondary phosphine Ph(PhCHCH)PH; however, complexes 3Ca and 4Ca led to the formation of both secondary and tertiary phosphines in 80:20 and 86:14 ratios. Styrene hydrophosphinations with 2,4,6-MeCHPH and 2-pyridylphosphine for all complexes 1Yb and 1-4Ca proceeded much more slowly compared to PhPH. Addition of 2-CNHPH to styrene catalyzed by complex 1Yb turned out to be non-regioselective and led to the formation of a mixture of Markovnikov and anti-Markovnikov addition products, while all Ca complexes enabled regioselective anti-Markovnikov addition. Complexes 1Ca and 1Yb containing catalytic centers featuring similar ionic radii performed different catalytic activity: the ytterbium analogue proved to be a more active catalyst for intermolecular hydrophosphination of styrene with CyPH, 2-CNHPH, and PhPH, but less active with sterically demanding 2,4,6-MeCHPH. Styrenes containing in p-position electron-donating groups (Me, tBu, OMe) performed with noticeably lower rates in the reactions with PhPH compared to styrene. Complexes 1Yb, 1Ca, 2Ca, 3Ca, and 4Ca enabled addition of PhPH toward the double C═C bond of α-Me-styrene, and the reaction rate for this substrate is noticeably lower; however quantitative conversions were reached in ∼40 h. Complexes 1Ca and 2Ca promoted 1,2-addition of PhPH to 2,3-dimethyl butadiene with excellent regio- and chemoselectivity to afford linear secondary phosphines. Hydrophosphination of inert 1-nonene with PhPH with 40% conversion becomes possible due to the application of complex 2Ca (40 h, 70 °C). The rate law for the hydrophosphination of styrene with PhPH catalyzed by 1Ca was found to agree with the idealized equation: v = k[styrene][1Ca].
通过前体配体LH与双酰胺基配合物MN(SiMe)（M = Yb，Ca）之间的转氨反应，合成了一系列由脒基-氨基吡啶配体L配位的酰胺基钙和镱（II）配合物LMN(SiMe)（1Yb，1 - 4Ca）。YbN(SiMe)与含有CF和CHF片段的前体配体LH - LH的反应无法制备目标Yb（II）配合物，而相应的钙类似物则能以良好的产率合成。对配合物1Yb和1 - 4Ca作为苯乙烯、对取代苯乙烯、α - 甲基苯乙烯和2,3 - 二甲基丁二烯与各种伯膦和仲膦（PhPH、2,4,6 - MeCHPH、2 - CNHPH、PhPH、CyPH）进行氢膦化反应的预催化剂进行了评估。配合物1Yb、1 - 4Ca在苯乙烯与PhPH和PhPH的氢膦化反应中表现出高催化活性，并表现出高区域选择性，仅生成反马氏加成产物。对于伯膦PhPH（底物摩尔比为1:1），由1Yb、1Ca和2Ca催化的反应具有高度的化学选择性，生成仲膦Ph(PhCHCH)PH；然而，配合物3Ca和4Ca导致生成仲膦和叔膦，比例为80:20和86:14。与PhPH相比，所有配合物1Yb和1 - 4Ca催化的苯乙烯与2,4,6 - MeCHPH和2 - 吡啶基膦的氢膦化反应进行得要慢得多。配合物1Yb催化苯乙烯与2 - CNHPH的加成反应没有区域选择性，导致生成马氏加成产物和反马氏加成产物的混合物，而所有钙配合物都能实现区域选择性的反马氏加成。含有具有相似离子半径催化中心的配合物1Ca和1Yb表现出不同的催化活性：镱类似物被证明是苯乙烯与CyPH、2 - CNHPH和PhPH进行分子间氢膦化反应的更活跃催化剂，但对空间位阻较大的2,4,6 - MeCHPH的活性较低。与苯乙烯相比，在对位含有给电子基团（Me、tBu、OMe）的苯乙烯与PhPH的反应速率明显较低。配合物1Yb、1Ca、2Ca、3Ca和4Ca能使PhPH加成到α - 甲基苯乙烯的C═C双键上，该底物的反应速率明显较低；然而，在约40小时内达到了定量转化。配合物1Ca和2Ca促进了PhPH对2,3 - 二甲基丁二烯的1,2 - 加成，具有优异的区域和化学选择性，生成线性仲膦。由于使用配合物2Ca（40小时，70°C）实现了40%转化率的惰性1 - 壬烯与PhPH的氢膦化反应。发现由1Ca催化的苯乙烯与PhPH的氢膦化反应速率定律符合理想方程：v = k[苯乙烯][1Ca]。
