Bronsted Acid Catalyzed, Conjugate Addition of β-Dicarbonyls to In Situ Generated ortho-Quinone Methides-Enantioselective Synthesis of 4-Aryl-4H-Chromenes
Bronsted Acid Catalyzed, Conjugate Addition of β-Dicarbonyls to In Situ Generated ortho-Quinone Methides-Enantioselective Synthesis of 4-Aryl-4H-Chromenes
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DOI：
10.1002/anie.201403573
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发表时间：
2014-07-21
影响因子：
16.6
通讯作者：
Schneider, Christoph
中科院分区：
文献类型：
--
作者：
El-Sepelgy, Osama;Haseloff, Stefan;Schneider, Christoph
本文描述了一种催化、对映选择性合成4H-色烯的方法，4H-色烯是许多天然产物和生物活性化合物的重要结构元素。一种由β-二酮与原位生成的邻苯二酚甲基化合物共轭加成，然后进行环脱水反应的序列，以通常良好的产率和较高的光学纯度提供了4-芳基-4H-色烯。以BINOL为基础的手性磷酸作为Bronsted酸催化剂，将邻羟基苯甲醇转化为氢键邻苯二酮亚甲基，并以较高的对映选择性影响了碳-碳键的形成。
We describe herein a catalytic, enantioselective process for the synthesis of 4H-chromenes which are important structural elements of many natural products and biologically active compounds. A sequence comprising a conjugate addition of beta-diketones to in situ generated ortho-quinone methides followed by a cyclodehydration reaction furnished 4-aryl-4H-chromenes in generally excellent yields and high optical purity. A BINOL-based chiral phosphoric acid was employed as a Bronsted acid catalyst which converted ortho-hydroxy benzhydryl alcohols into hydrogen-bonded ortho-quinone methides and effected the carbon-carbon bond-forming event with high enantioselectivity.