PALLADIUM-CATALYZED FORMYLATION OF ORGANIC HALIDES WITH CARBON-MONOXIDE AND TIN HYDRIDE
PALLADIUM-CATALYZED FORMYLATION OF ORGANIC HALIDES WITH CARBON-MONOXIDE AND TIN HYDRIDE
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DOI：
10.1021/ja00263a015
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发表时间：
1986-02-05
影响因子：
15
通讯作者：
STILLE, JK
中科院分区：
文献类型：
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作者：
BAILLARGEON, VP;STILLE, JK
钯催化的多种有机底物（芳基碘化物、苄基卤化物、乙烯基碘化物、乙烯基三氟甲磺酸酯和烯丙基卤化物）与氢化锡和一氧化碳的甲酰化反应在温和条件下（50℃、1-3atm CO2和2.5-3.5小时反应时间）可得到良好的醛收率，并且可耐受多种官能团。通过缓慢添加氢化三丁基锡和较高的一氧化碳压力，可以最大限度地减少竞争性副反应，即卤化物或三氟甲磺酸盐的直接还原。一般来说，卤代芳基上的给电子或吸电子取代基对甲酰化反应没有影响；然而，对硝基取代基会导致醛的产率显着降低。亲电子试剂的空间位阻会降低产率。不对称烯丙基卤化物的甲酰化是区域选择性的，发生在取代较少的烯丙基位置，并保留烯丙基双键的几何形状。在乙烯基碘的甲酰化中也观察到双键几何结构的保留。尽管有多种方法可用于从羧酸及其衍生物制备醛，但大多数都涉及金属氢化物作为还原剂。 1 氢气2（罗森蒙德还原）或氢化硅3 在钯催化剂存在下已成功用于将酰基氯还原为醛。通过在 80-100 C 下使用一氧化碳和氢气 (1:1, 1200-1500 psi)，可以将多种有机卤化物转化为醛。当使用氢化硅作为氢化物源时，4 芳基卤化物可以在较低的一氧化碳压力下甲酰化。 5 然而，这些制备醛的途径并非没有缺点，因为反应范围有些有限。分子中的其他可还原官能团通常是不能容忍的，并且经常观察到醛过度还原为醇，产物醇经常进一步反应。三丁基氢化锡是一种相对温和的金属氢化物还原剂，已用于醛的制备。尽管三丁基氢化锡对酰基氯的无催化还原产生了醛和酯的混合物6（从醛过度还原为醇），但钯催化剂的引入几乎仅将还原引导至醛。 7 该反应在温和条件和其他可还原基团存在下发生。但这种转变是有限度的
The palladium-catalyzed formylationof a wide variety of organic substrates (aryl iodides, benzyl halides, vinyl iodides, vinyl triflates, and allylic halides) with tin hydride and carbon monoxide gives good yields of aldehydes under mild conditions (50 C, 1-3atm of CO, and 2.5-3.5-h reaction times) and tolerates a number of functional groups. A competitive side reaction, the direct reduction of the halide or triflate, could be minimized by the slow addition of tributyltin hydrideand higher pressures of carbon monoxide. In general, electron-donating or-withdrawing substituents on the aryl halide have no effect on the formylation reaction; however, a p-nitro substituent causes significant reduction in the yield of aldehyde. Yields are diminished by steric hindrance about the electrophile. The formylation of uasymmetrical allyl halides is regioselective, taking place at the less substituted allylic position, with retention of geometry at the allylic double bond. Retention of the double bond geometry also is observed in the formylation of vinyl iodides.Although a variety of methods are available for the preparation of aldehydes from carboxylic acids and their derivatives, most involve metallic hydrides as reducing agents. 1 Hydrogen2 (Rosenmund reduction) or silicon hydrides, 3 in the presence of a palladium catalyst, have been successfully employedin reducing acid chlorides to aldehydes. The conversion of a number of organic halides into aldehydes has been accomplished by using carbon monoxide and hydrogen (1: 1, 1200-1500 psi) at 80-100 C. 4 Aryl halides can be formylated under lower carbon monoxide pressures when silicon hydrides are utilized as the hydride source. 5 These routes to aldehydes are not withouttheir disadvantages, however, since the scope of the reaction is somewhat limited. Other reducible functionality in the molecule cannot usually be tolerated, and overreduction of the aldehyde to the alcohol is often observed, theproduct alcohol often reacting further. Tributyltin hydride is a relatively mild metal hydride reducing reagent, which has been employed for the preparation of aldehydes. Although the uncatalyzed reduction of acid chlorides by tributyltin hydride yields a mixture of aldehydes and esters6 (from overre-duction of the aldehyde to alcohol), the introduction of a palladium catalyst directs the reduction nearly exclusively to the aldehyde. 7 The reaction occurs under mild conditions and in the presence of other reducible groups. However, this transformation is limited