Catalyst-Free Synthesis of Borylated Lactones from Esters via Electrophilic Oxyboration.
Catalyst-Free Synthesis of Borylated Lactones from Esters via Electrophilic Oxyboration.
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DOI：
10.1021/jacs.5b12989
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发表时间：
2016-02-24
影响因子：
15
通讯作者：
Blum SA
中科院分区：
文献类型：
--
作者：
Faizi DJ;Issaian A;Davis AJ;Blum SA
发展了一种无催化剂的炔硼氧化反应。将所得硼化异香豆素和2-吡喃酮分离为硼酸、频哪醇硼酸酯或有机三氟硼酸钾盐，为下游官能化提供多种工作台稳定的有机硼结构单元。该方法具有官能团相容性，可扩展，并且使用容易获得的材料进行：B-氯儿茶酚硼烷和甲酯。机理研究表明，B-氯儿茶酚硼烷作为亲碳刘易斯酸作用于炔，提供了一个独特的硼氧化途径，避免了B-O σ键的形成，并使这种无催化剂的路线。
A catalyst-free oxyboration reaction of alkynes is developed. The resulting borylated isocoumarins and 2-pyrones are isolated as boronic acids, pinacolboronate esters, or potassium organotrifluoroborate salts, providing a variety of bench-stable organoboron building blocks for downstream functionalization. This method has functional group compatibility, is scalable, and proceeds with readily available materials: B-chlorocatecholborane and methyl esters. Mechanistic studies indicate that the B-chlorocatecholborane acts as a carbophilic Lewis acid toward the alkyne, providing a mechanistically distinct pathway for oxyboration that avoids B–O σ bond formation and enables this catalyst-free route.