3,5-Dichloroisothiazole-4-carbonitrile 1 reacts with aryl- and methylboronic acids to give in high yields the 3-chloro-5-(aryl and methyl)-isothiazole-4-carbonitrile 2 regiospecifically. The reaction was optimized with respect to base, phase transfer agent and palladium catalyst. Suzuki coupling at C-5 was also achieved in high yield using potassium phenyltrifluoroborate. The regiospecificity of either coupling method is maintained with 3,5-dibromoisothiazole-4-carbonitrile 4 to give exclusively 3-bromo-5-phenylisothiazole-4-carbonitrile 5. Suzuki cross-coupling conditions applied to 3-chloro-5-phenylisothiazole-4-carbonitrile 2a gave 3-phenoxy-5-phenylisothiazole-4-carbonitrile 6, which was prepared independently, and not the 3-phenyl derivative. All isothiazole products were fully characterized.
3,5-二
氯异噻唑-4-甲腈 1 与芳基酸和甲基
硼酸反应,可以高产 3-
氯-5-(芳基和甲基)
异噻唑-4-甲腈 2。该反应在碱、相转移剂和
钯催化剂方面进行了优化。使用苯基三
氟硼酸钾也在 C-5 处实现了高产率的铃木偶联。在 3,5-二
溴异噻唑-4-甲腈 4 中,这两种偶联方法都保持了区域特异性,只得到 3-溴-
5-苯基异噻唑-4-甲腈 5。在
3-氯-5-苯基异噻唑-4-甲腈 2a 的铃木交叉偶联条件下,得到了独立制备的 3-苯氧基-
5-苯基异噻唑-4-甲腈 6,而不是 3-苯基衍
生物。所有
异噻唑产品均已完全表征。