Hiraoka Yuta, Imagawa Taiki, Nakanishi Kazuki, Kawabe Hinata, Nakamoto Masaaki, Tsushima Takumi, Yoshida Hiroto
Graduate School of Advanced Science and Engineering, Hiroshima University Higashi-Hiroshima 739-8526 Japan
Chem Sci. 2024 Aug 22;15(37):15152-9. doi: 10.1039/d4sc04526b.
Organometallic reagents such as organolithium and Grignard reagents have long been esteemed in chemical synthesis for their exceptional reactivity. In contrast, the application of their sodium and potassium counterparts has been comparatively sluggish, notwithstanding their augmented reactivity stemming from their heightened ionic character. This inertia persists due to the constrained accessibility of these heavy alkali metal reagents. In this study, our focus was directed towards devising a convenient and pragmatic approach for fabricating heavy alkali metal-based reagents, particularly those grounded in potassium. Herein, we present a novel, direct method for generating stannylpotassium (Sn-K) reagents through the simple combination of readily available silylstannanes and -BuOK. Subsequently, the generated Sn-K reagents were effectively harnessed for stannylative substitution of aryl halides, furnishing an array of arylstannanes straightforwardly under transition metal-free conditions. This application distinctly underscores the potential utility of highly reactive Sn-K species, hitherto sparingly tapped into within the realm of synthetic organic chemistry. Furthermore, our investigation confirms that Sn-K reagents manifest notably superior reactivity compared with their well-established stannyllithium (Sn-Li) counterparts. This heightened reactivity can be ascribed to the increasing ionic character of Sn-K, which was supported by computational experiments.
有机金属试剂,如有机锂试剂和格氏试剂,长期以来因其卓越的反应活性而在化学合成中备受推崇。相比之下,它们的钠和钾同类物的应用相对滞后,尽管它们因离子性增强而具有更高的反应活性。这种惰性持续存在是由于这些重碱金属试剂的可及性受限。在本研究中,我们的重点是设计一种方便实用的方法来制备基于重碱金属的试剂,特别是那些基于钾的试剂。在此,我们提出了一种新颖的直接方法,通过将容易获得的硅烷基锡烷和叔丁醇钾简单混合来生成锡基钾(Sn-K)试剂。随后,所生成的Sn-K试剂被有效地用于芳基卤化物的锡基取代反应,在无过渡金属条件下直接提供了一系列芳基锡烷。这一应用明显突出了高反应活性的Sn-K物种在合成有机化学领域迄今尚未充分利用的潜在用途。此外,我们的研究证实,Sn-K试剂表现出比其成熟的锡基锂(Sn-Li)同类物明显更高的反应活性。这种更高的反应活性可归因于Sn-K离子性的增加,这得到了计算实验的支持。