College of Chemistry and Chemical Engineering and State Key Laboratory of Applied Organic Chemistry, Lanzhou University, Lanzhou, People's Republic of China.
Chirality. 2011 Jan;23(1):69-75. doi: 10.1002/chir.20864.
Two new chiral dinuclear Mn(III)-Salen complexes with inherent phase-transfer capability have been synthesized, which serve as catalysts in the asymmetric epoxidation of nonfunctionalized alkenes. Experimental results show these complexes are effective catalysts for the asymmetric epoxidation of some cyclic alkenes and the catalysts have certain inherent phase-transfer capability during the epoxidation because of their weak water solubility. In general, good enantioselectivity and acceptable yields were achieved when NaClO was used as oxidant under three different reaction systems. Among these alkenes, the catalyst 6a gave the highest ee (94%) for 6-chloro-2,2-dimethylchromene in the presence of ionic liquid 2. Additionally, the recovery and recycling of one dimeric Mn(III)-Salen complex were tested to investigate atom efficiency of the catalyst in different reaction systems on the alkenes epoxidations. The catalyst 6a could be recovered and recycled for six times without losing activity and selectivity.
已经合成了两个具有内在相转移能力的新型手性双核 Mn(III)-Salen 配合物，它们可用作非官能化烯烃不对称环氧化的催化剂。实验结果表明，这些配合物是一些环状烯烃不对称环氧化的有效催化剂，由于其弱水溶性，在环氧化过程中具有一定的固有相转移能力。一般来说，当以 NaClO 作为氧化剂，在三种不同的反应体系下，都能得到良好的对映选择性和可接受的产率。在这些烯烃中，在离子液体 2 的存在下，催化剂 6a 对 6-氯-2,2-二甲基色烯的 ee 值（94%）最高。此外，还测试了一个二聚 Mn(III)-Salen 配合物的回收和循环利用，以研究催化剂在不同反应体系下对烯烃环氧化的原子效率。催化剂 6a 可以回收和循环使用六次，而不损失活性和选择性。
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