作者:Irene C. Christoforou、Panayiotis A. Koutentis
DOI:10.1039/b607442a
日期:——
Regioselective palladium catalysed coupling reactions are achieved in good to high yields, starting from either 3,5-dichloro- or 3,5-dibromoisothiazole-4-carbonitriles 1 and 2, providing 3-halo-5-(hetero/aryl, alkenyl and alkynyl)isothiazoles 3, 4, 6â9 from Stille couplings, 3-halo-5-(hetero/arylethynyl)isothiazoles 14â19 from Sonogashira and 5,5â²-bi(3-chloroisothiazole-4-carbonitrile) (13) from an Ullmann type coupling. 3,5-Dibromoisothiazole-4-carbonitrile 2 is more reactive than the dichloroisothiazole-4-carbonitrile 1 and effective enough for Stille, Negishi and Sonogashira couplings. 5,5-Bi(3-chloroisothiazole-4-carbonitrile) (13) is prepared by a palladium catalysed Ullmann coupling from 3-chloro-5-iodoisothiazole-4-carbonitrile (11). A variety of 3-substituted isothiazoles (3-substituents = Cl, Br, OMs, OTs and OTf) are less reactive and fail to give successful Suzuki couplings at the isothiazole C-3 position. The 3-iodo-5-phenyl-isothiazole-4-carbonitrile (28), prepared via Sandmeyer iodination, participates successfully in Suzuki, Ullmann type, Stille, Negishi and Sonogashira coupling reactions. All products are fully characterized.
区域选择性钯催化的偶联反应以良好至高产率实现,从3,5-二氯或3,5-二溴异噻唑-4-腈1和2出发,通过Stille偶联反应得到3-卤代-5-(杂/芳基、烯基和炔基)异噻唑3、4、6–9,通过Sonogashira反应得到3-卤代-5-(杂/芳基炔基)异噻唑14–19,以及通过Ullmann型偶联反应得到5,5'-二(3-氯异噻唑-4-腈)13。3,5-二溴异噻唑-4-腈2比3,5-二氯异噻唑-4-腈1更具反应活性,足以有效进行Stille、Negishi和Sonogashira偶联反应。5,5-二(3-氯异噻唑-4-腈)13通过钯催化的Ullmann偶联反应由3-氯-5-碘异噻唑-4-腈11制备。多种3-取代异噻唑(3-取代基=Cl、Br、OMs、OTs和OTf)反应活性较低,未能成功在异噻唑C-3位置进行Suzuki偶联反应。通过Sandmeyer碘化法制备的3-碘-5-苯基异噻唑-4-腈28成功参与了Suzuki、Ullmann型、Stille、Negishi和Sonogashira偶联反应。所有产物均经过充分表征。