Synthesis of (<i>E</i>)-1-Aryl Alk-1-en-3-ones by Tetraphosphine/Palladium-Catalysed Heck Reactions of Alk-1-en-3-ones with Aryl Bromides
作者:Henri Doucet、Maurice Santelli、Mhamed Lemhadri
DOI:10.1055/s-2006-948174
日期:2006.11
The tetraphosphine cis,cis,cis-1,2,3,4-tetrakis(diphenylphosphinomethyl)cyclopentane in combination with [Pd(C3H5)Cl]2 affords a very efficient catalyst for the Heck reaction of alk-1-en-3-ones with aryl bromides. If appropriate reaction conditions are used (NaOAc as base, hydroquinone as stabilising agent and DMF as solvent) high yields of (E)-1-aryl alk-1-en-3-one derivatives are obtained. In general, higher reaction rates were observed with electron-poor aryl bromides, but the electron-rich aryl bromides 4-N,N-dimethylaminobromobenzene and 4-bromoanisole also led to the arylated enones. Even with sterically very congested aryl bromides such as 9-bromoanthracene, 2,4,6-trimethylbromobenzene or 2,4,6-triisopropylbromobenzene, the expected (E)-1-aryl alk-1-en-3-ones were obtained in moderate to good yields. Moreover, several reactions can be performed with as little as 0.1% catalyst.
四膦cis,cis,cis-1,2,3,4-四(二苯膦甲基)环戊烷与[Pd(C3H5)Cl]2结合,可以有效地催化烯-1-烯-3-酮与芳基溴化物的赫克反应。如果使用适当的反应条件(以醋酸钠为碱,羟基苯作为稳定剂,DMF作为溶剂),可以获得高产率的(E)-1-芳基烯-1-烯-3-酮衍生物。一般来说,使用电子贫乏的芳基溴化物时反应速率较高,但电子丰富的芳基溴化物4-N,N-二甲基氨基溴苯和4-溴苯醚也能生成芳基化的烯酮。即使是非常拥挤的芳基溴化物,如9-溴芴、2,4,6-三甲基溴苯或2,4,6-三异丙基溴苯,预期的(E)-1-芳基烯-1-烯-3-酮也以中等到良好的产率获得。此外,几乎可以仅用0.1%的催化剂进行多次反应。