Reductive Cyclization of Nitro and Azide Compounds with Aldehydes and Ketones Promoted by Metallic Samarium and Catalytic Amount of Iodine
Reductive Cyclization of Nitro and Azide Compounds with Aldehydes and Ketones Promoted by Metallic Samarium and Catalytic Amount of Iodine
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DOI：
10.1071/ch02117
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发表时间：
2002
影响因子：
1.1
通讯作者：
W. Su;Bibo Yang
中科院分区：
文献类型：
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作者：
W. Su;Bibo Yang
由于 Kagan 和他的团队的开创性研究证明了二碘化钐 (SmI2) 作为一种温和、中性、可溶于醚的单电子转移还原剂的特殊有效性，[1, 2] SmI2 在合成有机化学中的应用已被广泛记录。[3-10] 然而，当 SmI2 用作还原剂时可能会出现问题。 SmI2可在密封瓶中获得，但即使在短暂暴露于空气和/或湿气后也会失活，并且SmI2总是不能满足原子经济性的要求。另一方面，金属钐在空气中稳定，其强还原力（Sm3+/Sm=–2.41 V）与镁（Mg2+/Mg=–2.37 V）相似。最近人们注意到金属钐可以直接用于有机合成。[11-15]因此，我们希望使用更方便、更便宜的钐来代替SmI2，直接作为还原剂。 2, 3-二氢-2-芳基-4 (1H)-喹唑啉酮衍生物是药物化学的重要化合物。有些是除草剂和植物生长调节剂。[16, 17] 它们也用作利尿剂和抗肿瘤剂。[18, 19] 制备 2, 3-二氢-2-芳基-4 (1H)-喹唑啉酮的一般程序包括使用对甲苯磺酸作为催化剂在剧烈反应下将适当的 2-氨基苯甲酰胺与醛或酮缩合[20, 21]众所周知，硝基和叠氮化合物可以很容易地被金属钐和催化量的碘还原成相应的胺。[22, 23]然而，很少有人关注通过还原处理衍生自硝基或叠氮基团的中间体。[24]在我们之前的工作中，我们演示了二碘化钐诱导的叠氮化合物与腈的还原偶联。 [25]在此，我们希望报道硝基和叠氮化合物与醛和酮在金属钐和催化量的碘的催化下发生还原环化（方案1）。在氮气气氛下，在无水甲醇中用金属钐和催化量的碘处理邻硝基苯甲酰胺或邻叠氮基苯甲酰胺(1)后，
Since pioneering studies by Kagan and his group demonstrated the particular effectiveness of samarium diiodide (SmI2) as a mild, neutral, ether-soluble, one-electron transfer reducing agent,[1, 2] the utilization of SmI2 in synthetic organic chemistry has been extensively documented.[3–10] However, problems can arise when SmI2 is used as a reductant. SmI2 is available in sealed bottles, but can be inactivated even after a brief exposure to air and/or moisture, and SmI2 invariably cannot meet the demand of atom economy. On the other hand, metallic samarium is stable in air, and its strong reducing power (Sm3+/Sm=–2.41 V) is similar to that of magnesium (Mg2+/Mg=–2.37 V). It has been noted recently that metallic samarium can be used directly in organic synthesis.[11–15] As a result, we wish to use the more convenient and cheaper samarium, instead of SmI2, directly as a reductant. 2, 3-Dihydro-2-aryl-4 (1H)-quinazolinone derivatives are important compounds for pharmaceutical chemistry. Some are herbicides and plant-growth regulators.[16, 17] They are also used as diuretics and antitumour agents.[18, 19] A general procedure for the preparation of 2, 3-dihydro-2-aryl-4 (1H)-quinazolinones involves condensing the appropriate 2-aminobenzamide with an aldehyde or ketone using p-toluenesulfonic acid as a catalyst under vigorous reaction conditions.[20, 21]It is well known that nitro and azide compounds can easily be reduced to their corresponding amines by metallic samarium and catalytic amounts of iodine.[22, 23] However, little attention has been paid to the intermediate derived from a nitro or azide group by the reduction treatment.[24] In our previous work, we demonstrated the reductive coupling of azide compounds with nitriles induced by samarium diiodide.[25] Herein, we wish to report the reductive cyclization of nitro and azide compounds with aldehydes and ketones promoted by metallic samarium and catalytic amounts of iodine (Scheme 1). After treating o-nitrobenzamide or o-azidobenzamide (1) with metallic samarium and catalytic amounts of iodine in anhydrous methanol under a nitrogen atmosphere, the