Deprotonative Magnesation and Cadmation of [1,2,3]Triazolo[1,5-a]pyridines
Deprotonative Magnesation and Cadmation of [1,2,3]Triazolo[1,5-a]pyridines
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DOI：
10.1021/jo801675h
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发表时间：
2009-01-02
影响因子：
3.6
通讯作者：
Abarca, Belen
中科院分区：
文献类型：
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作者：
Bentabed-Ababsa, Ghenla;Blanco, Fernando;Abarca, Belen
[1，2，3]三唑并[1，5-a]吡啶和3-取代的衍生物在7位使用Bu 3 MgLi或（TMP）（3）CdLi进行区域选择性金属化，前者在-10 ℃下，后者在室温下。芳基镁酸锂（R = H，Me，Ph）与碘（34-75%）或3，4，5-三甲氧基苯甲醛（32-51%）反应。在钯催化下使用2-溴吡啶获得交叉偶联产物的尝试失败，这一结果归因于这些化合物的低稳定性。相应的芳基锌酸锂在相同的反应条件下以17-60%的产率反应。芳基镉酸锂可被碘捕获（38- 76%，R = H，Me，Ph，CN，2-噻吩基）或参与钯催化的与2-溴吡啶的交叉偶联反应（26- 67%，R = H，Me，Ph）。对于R = 2-吡啶基，分离得到3-（6-碘-2-吡啶基）-[1，2，3]三唑并[1，5-a]吡啶，产率为73%。（TMP）3CdLi也被证明适用于两种底物（R = H，2-噻吩基）的干净的双去质子化，通过用碘（66-75%）淬灭证实了这一结果。
[1,2,3]Triazolo[ 1,5-a]pyridine and 3-substituted derivatives were regioselectively metalated at the 7 position using either Bu3MgLi or (TMP)(3)CdLi, the former at -10 degrees C and the latter at room temperature. The lithium arylmagnesates (R = H, Me, Ph) proved to react with iodine (34-75%) or 3,4,5-trimethoxybenzaldehyde (32-51%). Attempts to obtain the cross-coupling products using 2-bromopyridine under palladium catalysis failed, a result attributed to the low stability of these compounds. The corresponding lithium arylzincates reacted in 17-60% yield under the same reaction conditions. The lithium arylcadmates were either trapped with iodine (38-76%, R = H, Me, Ph, CN, 2-thienyl) or involved in palladiumcatalyzed cross-coupling reactions with 2-bromopyridine (26-67%, R = H, Me, Ph). For R = 2-pyridyl, 3-(6-iodo-2-pyridyl)-[1,2,3]triazolo[1,5-a]pyridine was isolated in 73% yield. (TMP)3CdLi also proved suitable for the clean dideprotonation of two substrates (R = H, 2-thienyl), a result demonstrated by quenching with iodine (66-75%).