Bu3SnH-catalyzed Barton-McCombie deoxygenation of alcohols
Bu3SnH-catalyzed Barton-McCombie deoxygenation of alcohols
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DOI：
10.1021/ja971400y
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发表时间：
1997-07-23
影响因子：
15
通讯作者：
Fu, GC
中科院分区：
文献类型：
--
作者：
Lopez, RM;Hays, DS;Fu, GC
Barton-McCombie过程用于醇的脱氧(图1)1，2是一种非常有用的方法，在合成有机化学中得到了广泛的应用。3这种自由基介导的过程通常使用1.5-3当量的Bu3SnH作为还原剂。在本文中，我们描述了第一个以Bu3SnH为催化剂，以聚甲基氢硅氧烷(PMHS；TM O-(SiHMeO)n-TMS)为化学计量比还原剂的Barton-McCombie脱氧反应的催化变体。4不幸的是，一些含三丁基锡的化合物有毒，5这一事实刺激了Bu3SnH替代品的开发。6硅氢化物一直是人们关注的主要焦点，在许多情况下，它们被证明是Bu3SnH的合适替代品。7然而，也观察到了不同的反应活性，8正如预期的那样，基本上不同的化合物家族。与其因为担心毒性而放弃Bu3SnH，我们正在开发将其用作催化剂的工艺，并将其与一种无害的化学计量比还原剂结合使用。9、10这一策略允许我们利用Bu3SnH发达的、有时是独特的化学物质，同时极大地减少产生的有机锡残留量。这种方法在Bu3SnH催化的Barton-McCombie脱氧反应变体中的应用如图2所示。Bu3SnH还原硫代碳酸酯得到COS、所需的烷烃和Bu3-
The Barton-McCombie procedure for the deoxygenation of alcohols (Figure 1) 1, 2 is an extremely useful method that has found widespread application in synthetic organic chemistry. 3 This radical-mediated process typically employs 1.5-3 equiv of Bu3SnH as the reducing agent. In this paper, we describe the first catalyzed variant of the Barton-McCombie deoxygenation reaction, using Bu3SnH as the catalyst and polymethylhydrosiloxane (PMHS; TMSO-(SiHMeO) n-TMS) as the stoichiometric reductant (eq 1).Bu3SnH is an extraordinarily versatile reagent for organic synthesis. 4 Unfortunately, some tributyltin-containing compounds are toxic, 5 a fact that has stimulated the development of alternatives to Bu3SnH. 6 Silicon hydrides have been the primary focus of attention, and in a number of instances they have been shown to serve as suitable substitutes for Bu3SnH. 7 However, disparate reactivity has also been observed, 8 as would be expected for fundamentally distinct families of compounds. Rather than forsaking Bu3SnH due to concerns about toxicity, we are developing processes in which it is employed as a catalyst in conjunction with an innocuous stoichiometric reductant. 9, 10 This strategy allows us to exploit the welldeveloped, sometimes unique, chemistry of Bu3SnH while greatly diminishing the quantity of organotin residue that is generated. The application of this approach to a Bu3SnH-catalyzed variant of the Barton-McCombie deoxygenation reaction is outlined in Figure 2. The reduction of a thionocarbonate by Bu3SnH affords COS, the desired alkane, and Bu3-