Phosphoric Acid Catalyzed [4 + 1]-Cycloannulation Reaction of ortho-Quinone Methides and Diazoketones: Catalytic, Enantioselective Access toward cis-2,3-Dihydrobenzofurans.
Phosphoric Acid Catalyzed [4 + 1]-Cycloannulation Reaction of ortho-Quinone Methides and Diazoketones: Catalytic, Enantioselective Access toward cis-2,3-Dihydrobenzofurans.
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DOI：
10.1021/acs.orglett.8b03311
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发表时间：
2018-11
期刊：
影响因子：
5.2
通讯作者：
Arun Suneja;C. Schneider
中科院分区：
文献类型：
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作者：
Arun Suneja;C. Schneider
通过将 α-重氮羰基化合物添加到由手性布朗斯台德酸催化的原位生成的 o-QM 中，实现了一种高度直接的对映体高度富集的顺式-2,3-二氢苯并呋喃的路线。这种催化策略可以在环境温度下以高收率直接获得 2,3-二氢苯并呋喃，dr 和 er 比例高达 91:9 和 99:1。此外，独特的苯鎓型重排导致产物形成具有反向2,3-取代模式。
A highly straightforward route to enantiomerically highly enriched cis-2,3-dihydrobenzofurans has been achieved via addition of α-diazocarbonyl compounds to in situ generated o-QMs catalyzed by a chiral Brønsted acid. This catalytic strategy provides a direct access to 2,3-dihydrobenzofurans in high yields and with up to 91:9 dr and 99:1 er at ambient temperature. Moreover, a unique phenonium-type rearrangement accounts for product formation with an inverted 2,3-substitution pattern.