Indium-catalyzed retro-claisen condensation
Indium-catalyzed retro-claisen condensation
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DOI：
10.1002/anie.200702798
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发表时间：
2007-01-01
影响因子：
16.6
通讯作者：
Takai, Kazuhiko
中科院分区：
文献类型：
--
作者：
Kawata, Atsushi;Takata, Kazumi;Takai, Kazuhiko
酯类化合物是日常生活、学术和工业实验室中不可缺少的化合物。因此，合成酯的有效方法是很重要的。[1]到目前为止，已经使用了各种方法，包括醇和羧酸、[2，3]酸酐、[4]或酰基卤化物的缩合反应；[5]酯交换反应；[6]酯交换反应；[7]汞催化的羧酸与乙炔的反应；[8]和酶催化的方法。[9]最近，通过碳-碳键断裂的化学转化受到了极大的关注，因为这样的反应可以直接构建新的骨架。[10]本文报道了铟催化的碳-碳键断裂，即逆克莱森缩合反应。[11]2，4-戊二酮(1a)和2-苯乙醇(2a)在[{REBR(CO)3(THF)}2]作为催化剂，在808℃下反应24 h，得到了乙酸苯乙酯(3a)，产率为49%(表1，条目1)。在该反应中，起始原料1a和2a残留，丙酮作为单一副产物生成。在没有催化剂的情况下，反应无法进行(表1，条目9)。为了提高乙酸乙酯的产率，
Esters are indispensable compounds both in daily life and in academic and industrial laboratories. Thus, efficient methods for synthesizing esters are important.[1] To date, various methods have been employed for this purpose, including condensation of alcohols and carboxylic acids,[2, 3] acid anhydrides,[4] or acyl halides;[5] transesterification;[6] ester-interchange reactions;[7] mercury-catalyzed reaction of carboxylic acids with acetylenes;[8] and enzyme-catalyzed methods.[9] Recently, chemical transformations via carbon–carbon bond cleavage have received much attention, because new skeletons can be constructed directly by using such reactions.[10] We report herein indium-catalyzed synthesis of esters via carbon–carbon bond cleavage, that is, retro-Claisen condensation.[11]The reaction of 2, 4-pentanedione (1a) with 2-phenylethanol (2a) in the presence of [{ReBr (CO) 3 (thf)} 2] as the catalyst at 808C for 24 h gave phenethyl acetate (3a) in 49% yield (Table 1, entry 1). In this reaction, starting materials 1a and 2a remained, and acetone was formed as a single side product. The reaction did not proceed in the absence of the catalyst (Table 1, entry 9). To improve the yield of the acetate,