Transition-Metal-Free Synthesis of Borylated Thiophenes via Formal Thioboration
Transition-Metal-Free Synthesis of Borylated Thiophenes via Formal Thioboration
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DOI：
10.1021/acs.orglett.8b02727
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发表时间：
2018-11-02
期刊：
影响因子：
5.2
通讯作者：
Blum, Suzanne A.
中科院分区：
文献类型：
--
作者：
Abed, Hassen Bel;Blum, Suzanne A.
报道了一种简单、区域控制且不含过渡金属的方法来专门获得3-硼基化噻吩衍生物。市售的B-氯儿茶酚硼烷试剂（ClBcat）充当亲碳刘易斯酸以活化容易合成的（Z）-有机基噻吩炔底物中的炔。这种硼诱导的活化引发了正式的硫代硼化和随后的硫脱烷基化，导致以良好的产率形成3-硼基化噻吩。所得硼基化噻吩可分离为硼酸酯（Bpin）和硼酰胺（Bdan）。这些硼基化产物适合于不同的下游官能化反应，即，通过交叉偶联、叠氮化、溴化和C-H活化形成C-C键。
A simple, regiocontrolled, and transition-metal-free approach to access exclusively 3-borylated thiophene derivatives is reported. The commercially available B-chlorocatecholborane reagent (ClBcat) acts as a carbophilic Lewis acid to activate the alkyne in readily synthesized (Z)-organylthioenyne substrates. This boron-induced activation initiates the formal thioboration and subsequent sulfur dealkylation, leading to the formation of 3-borylated thiophenes in good yields. The resulting borylated thiophenes are isolable as boronic esters (Bpin) and boronamides (Bdan). These borylated products are amenable to diverse downstream functionalization reactions, i.e., C-C bond formation through cross-coupling, azidation, bromination, and C-H activation.