HKUST-1单位点铜催化CO2/CS2成环耦合三氟甲基化反应

Cyclization of carbon CO2/CS2 coupled with trifluoromethylation catalyzed by single-site copper within HKUST-1

摘要:

以烯丙基胺类为底物，Togni's Reagent Ⅱ〔1-（三氟甲基)-1,2-苯碘酰-3(1H)-酮〕为三氟甲基源，CO2或CS2为C1合成子，高稳定性金属有机框架HKUST-1的Cu2(O2C)4双轮桨节点的单位点铜为催化剂，在温和条件下耦合CO2/CS2成环与三氟甲基化反应。对碱性添加剂、溶剂、反应温度、催化剂负载量等反应条件进行了优化。结果表明，在5%的HKUST-1〔基于Cu2(O2C)4双轮桨节点，催化剂最简分子结构为Cu2(BTC)4/3·2H2O，相对分子量为439.28 g/mol〕、CO2压力为101.325 kPa、45 ℃的最佳反应条件下，含不同取代基的底物能以69%～87%的产率得到三氟甲基-噁唑烷酮医药中间体。自由基捕获实验验证了该反应可能的反应机理。催化剂HKUST-1可循环使用5次仍保持良好催化活性和晶态结构。使用CS2替代CO2时，可得到具有中枢神经调节作用的三氟甲基-噻唑烷硫酮衍生物，体现出该体系对硫毒化的耐受性。

Abstract:

Cyclization of CO2 (or CS2) coupled with trifluoromethylation was carried out taking allylamine as substrate, Togni's reagent Ⅱ(1-(trifluoromethyl)-1,2-benziodoxol-3(1H)-one) as source of trifluoromethyl, single-site copper of highly stable metal-organic framework (MOF) HKUST-1〔based upon the Cu2(O2C)4 bis-paddelwheel, the simplest molecular structure of catalyst is Cu2(BTC)4/3·2H2O, and the relative molecular weight is about 439.28 g/mol〕as catalyst. The factors affecting the reaction such as basic additive, solvent, reaction temperature, loading amount of HKUST-1 were optimized. The results showed that allylamine substrates bearing different substituent groups could been transformed into bioactive trifluoromethylated 2-oxazolidones in yields of 69%~87% under the optimal conditions of 5% HKUST-1, CO2 pressure 101.325 kPa , reaction temperature 45 ℃. The possible mechanism of the reaction was verified by free radical trapping experiment. The catalyst HKUST-1 could be easily recovered and reused for at least five times and still had good catalytic activity and crystal structure. When CS2 was used as C1 source instead of CO2, the analogue of central nervous system agent, trifluoromethylated 2-thiazolidinethione could be obtained, reflecting the durability of this heterogeneous catalytic system against sulfur-poisoning effect.