Hydrazine Hydrate Accelerates Neocuproine–Copper Complex Generation and Utilization in Alkyne Reduction, a Significant Supplement Method for Catalytic Hydrogenation

Abstract

Diimine (HNNH) is a strong reducing agent, but the efficiency of diimine oxidized from hydrazine hydrate or its derivatives is still not good enough. Herein, we report an in situ neocuproine–copper complex formation method. The redox potential of this complex enable it can serve as an ideal redox catalyst in the synthesis of diimine by oxidation of hydrazine hydrate, and we successfully applied this technique in the reduction of alkynes. This reduction method displays a broad functional group tolerance and substrate adaptability as well as the advantages of safety and high efficiency. Especially, nitro, benzyl, boc, and sulfur containing alkynes can be reduced to the corresponding alkanes directly, which provides a useful complementary method to traditional catalytic hydrogenation. Besides, we applied this method in the preparation of the Alzheimer’s disease drug CT-1812 and studied the mechanism.

Modulating Charges of Dual Sites in Multivariate Metal–Organic Frameworks for Boosting Selective Aerobic Epoxidation of Alkenes

“…To explore the formation of Cu­(I) sites, the role of each component in reaction solution including DHTA, DMF, and ethanol is investigated by using the trapping agent neocuproine (2,9-dimethyl-1,10-phenanthroline) for Cu­(I) ions (Figure S29). UV–vis spectra show that a characteristic peak at ∼458 nm for Cu­(I) ions is observed when precursor Cu­(II) ions are dissolved in DMF at 100 °C for 2 h, indicative of occurrence of reduction of Cu­(II) to Cu­(I) ions . In contrast, almost no reduction of Cu­(II) ions happens when DMF is replaced by ethanol and DHTA under identical conditions.…”

“…UV−vis spectra show that a characteristic peak at ∼458 nm for Cu(I) ions is observed when precursor Cu(II) ions are dissolved in DMF at 100 °C for 2 h, indicative of occurrence of reduction of Cu(II) to Cu(I) ions. 59 In contrast, almost no reduction of Cu(II) ions happens when DMF is replaced by S30). Note that no signal of the carbonyl group of quinone in the Cu 1/2 Zn 1/2 -MOF-74 is observed at around 180 ppm (Figure S31).…”

Copper and neocuproine catalysed synthesis of cinnamyl ether derivatives directly from secondary and tertiary cinnamyl alcohols

“…This result demonstrated that the oxygen atom of the ether comes from the primary alcohol or secondary and tertiary cinnamyl alcohols. Based on the experimental findings and literature reported results, 26,27 a possible mechanism was proposed (Scheme 2-2). Cu 2+ and neocuproine formed a neocuproine 2 –Cu II complex at first (confirmed by high resolution mass spectrometry in ESI 5.3†), then the neocuproine 2 –Cu II complex was attacked by benzyl alcohol and a new quadrilateral planar coordination complex A was formed.…”