A new efficient route to 2-substituted azulenes based on sulfonyl group directed lithiation.
A new efficient route to 2-substituted azulenes based on sulfonyl group directed lithiation.
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基于磺酰基定向锂化的 2-取代甘菊环的新有效路线。
DOI：
10.1021/jo801166f
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发表时间：
2008
期刊：
影响因子：
--
通讯作者：
Y. Sugihara
中科院分区：
文献类型：
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作者：
Toshihisa Shibasaki;Takeo Ooishi;Nobuhiko Yamanouchi;T. Murafuji;Kei Kurotobi;Y. Sugihara
用2，2，6，6-四甲基哌啶锂（LTMP）实现了对甲苯基1-奥基砜（1）在奥基2位的直接锂化。由此产生的甘菊环基锂可以被各种亲电试剂有效地捕获，以中等至良好的产率形成2-取代的衍生物2。对甲苯基2-三甲基硅基-1-甘菊环砜（2a）通过对甲苯基的直接锂化和随后的8位分子内闭环转化为环状砜衍生物3a。2-（苯硫基）-1-甘菊环基对甲苯基砜（2b）发生双磺酰化反应生成2-苯硫基甘菊环（4）。2-碘代-1-奥基对甲苯基砜（2d）与芳基硼酸的Suzuki偶联反应，然后进行N-甲基-苯基-磺酰基化，有效地得到了2-芳基奥基10。
Directed lithiation of p-tolyl 1-azulenyl sulfone (1) at the 2-position of the azulenyl group was achieved by using lithium 2,2,6,6-tetramethylpiperidide (LTMP). The azulenyllithium thus generated could be efficiently trapped with various electrophiles to form 2-substituted derivatives 2 in moderate to good yields. p-Tolyl 2-trimethylsilyl-1-azulenyl sulfone (2a) was transformed into cyclic sulfone derivative 3a through the directed lithiation in the p-tolyl group and subsequent intramolecular ring closure at the 8-position. 2-(Phenylsulfanyl)-1-azulenyl p-tolyl sulfone (2b) suffered from desulfonylation to form 2-phenylsulfanylazulene (4). The Suzuki coupling reaction of 2-iodo-1-azulenyl p-tolyl sulfone (2d) with arylboronic acids followed by desulfonylation efficiently gave 2-arylazulenes 10.