4,5,6,7-Tetrachlorobenzo[d][1,3,2]dioxaborol-2-ol as an effective catalyst for the amide condensation of sterically demanding carboxylic acids
4,5,6,7-Tetrachlorobenzo[d][1,3,2]dioxaborol-2-ol as an effective catalyst for the amide condensation of sterically demanding carboxylic acids
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DOI：
10.1021/ol060216r
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发表时间：
2006-03-30
期刊：
影响因子：
5.2
通讯作者：
Yamamoto, H
中科院分区：
文献类型：
--
作者：
Maki, T;Ishihara, K;Yamamoto, H
4，5，6，7-四氯苯并[d][1，3，2]二氧硼杂环戊烯（4a）和4，5，6，7-四氯苯并[d][1，3，2]二氧硼杂环戊烯-2-醇（4 b）是羧酸和胺等摩尔混合物脱水酰胺缩合反应的有效催化剂。特别地，这些催化剂对于空间要求高的羧酸的酰胺缩合大大上级3，5-双（三氟甲基）苯基硼酸（1）。相比之下，由B（OH）3和四氯邻苯二酚的1：2摩尔混合物制备的4c作为用于Ritter反应的刘易斯酸辅助的布朗斯台德酸（LBA）催化剂是有效的。
4,5,6,7-Tetrachlorobenzo[d][1,3,2]dioxaborole (4a) and 4,5,6,7-tetrachlorobenzo[d][1,3,2]dioxaborol-2-ol (4b) are effective catalysts for the dehydrative amide condensation between an equimolar mixture of carboxylic acids and amines. In particular, these catalysts are greatly superior to 3,5-bis(trifluoromethyl)phenylboronic acid (1) for the amide condensation of sterically demanding carboxylic acids. In contrast, 4c, which is prepared from a 1:2 molar mixture of B(OH)3 and tetrachlorocatechol, is effective as a Lewis acid-assisted Bronsted acid (LBA) catalyst for Ritter reaction.