SYNTHETICALLY USEFUL ARYL ARYL BOND FORMATION VIA GRIGNARD GENERATION AND TRAPPING OF ARYNES - A ONE-STEP SYNTHESIS OF PARA-TERPHENYL AND UNSYMMETRIC BIARYLS
SYNTHETICALLY USEFUL ARYL ARYL BOND FORMATION VIA GRIGNARD GENERATION AND TRAPPING OF ARYNES - A ONE-STEP SYNTHESIS OF PARA-TERPHENYL AND UNSYMMETRIC BIARYLS
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DOI：
10.1021/jo00217a018
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发表时间：
1985-01-01
影响因子：
3.6
通讯作者：
DU, CJF
中科院分区：
文献类型：
--
作者：
HART, H;HARADA, K;DU, CJF
描述了一种一锅法合成对三联苯的方法。将1，4-二溴-2，5-二碘苯1与过量的芳基格氏试剂加成，得到三联苯二格氏试剂2和三卤代单格氏试剂5.在水淬灭之后，以30%至50+%的产率分离对三联苯（表I）。通过在后处理之前向反应混合物中加入叔丁醇钾或四甲基哌啶锂，该产率可提高至70-80%。提出了涉及有机金属芳炔中间体的机制。用邻-溴碘代芳烃代替四卤代芳烃，该方法可适于以良好的产率制备不对称联芳基化合物（表II）。芳基-芳基键的形成仍然是有机合成中的重要问题，并且已知大量实现该结构的方法。[2，3]仍在使用的著名方法，通常经过改进，包括Ullmann，Pschorr和Gomberg-Bachmann-Hey反应，以及联苯胺重排。较新的方法主要涉及芳烃、芳基卤、酚和其它芳族衍生物的氧化偶联，使用过渡金属、化学氧化剂或电化学方法作为试剂。1 234照片-
A one-pot route to p-terphenyls is described. Addition of l, 4-dibromo-2, 5-diiodobenzene, 1, to excess aryl Grignard reagent gives the terphenyl di-Grignard 2 and the trihalo mono-Grignard 5. After aqueous quench, p-terphenyls are isolated in 30% to 50+% yield (Table I). This yield can be improved to 70-80% by adding potassium tert-butoxide or lithium tetramethylpiperidide to the reaction mixture prior to workup. Mechanisms involving organometallic aryne intermediates are proposed. With o-bromoiodoarenes in place of tetrahaloarenes the method can be adapted to prepare unsymmetric biaryls in good yield (Table II).The formation of aryl-aryl bonds continues to be an important problem in organic synthesis, and a substantial number of methods for effecting this construction are known. 2, 3 Venerable methods still used, often with improved modifications, include the Ullmann, the Pschorr and Gomberg-Bachmann-Hey reactions, and the benzi-dine rearrangement. Newer methods involve mainly ox-idative coupling of arenes, aryl halides, phenols, and other aromatic derivatives, using as reagents transition metals, chemical oxidants, or electrochemical methods. 1 234 Photo-