Synthesis of chiral C2-symmetric methylene- and boron-bridged bis(imidazolines)
Synthesis of chiral C2-symmetric methylene- and boron-bridged bis(imidazolines)
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DOI：
10.1055/s2007-965897
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发表时间：
2007-02-15
影响因子：
2.6
通讯作者：
Pfaltz, Andreas
中科院分区：
文献类型：
--
作者：
Ramalingam, Balamurugan;Neuburger, Markus;Pfaltz, Andreas
通过2-咪唑啉的锂化并随后与二烷基或二芳基卤代硼烷反应获得一系列C-2-对称硼桥双(咪唑啉)。从 N-叔丁氧基羰基保护的 α-氨基酸开始，通过有效的四步序列制备相应的 2-咪唑啉。 C-2-对称亚甲基双(咪唑啉)很容易由手性二胺与丙二酰亚胺酸二乙酯缩合合成。双(咪唑啉)在苯乙烯的对映选择性环丙烷化和环烯烃的烯丙基氧化中用作配体。
A series of C-2-symmetric boron-bridged bis(imidazolines) was obtained by lithiation of 2-imidazolines and subsequent reaction with dialkyl- or diarylhaloboranes. The corresponding 2-imidazolines were prepared by an efficient four-step sequence starting from N-tert-butoxycarbonyl-protected alpha-amino acids. C-2-Symmetric methylenebis(imidazolines) were readily synthesized from chiral diamines by condensation with diethyl malonimidate. The bis(imidazolines) were used as ligands in the enantioselective cyclopropanation of styrene and allylic oxidation of cyclic alkenes.