Polyhedral Cu₂O Crystals for Diverse Aryl Alkyne Hydroboration Reactions

Abstract

Cu 2 Oc ubes,o ctahedra, and rhombic dodecahedra have been used to examine facet-dependent catalytic activity in aryl alkyneh ydroboration reactions. Althought he reaction can proceed by using ethanol or other alcohols as solvent, the use of 1,4-dioxane gave the bestp roduct yield. All particles hapes gave exclusively the E-product,b ut the rhombic dodecahedrae xposing {110} surfacesw ere consis-tently far more reactive than the other particlem orphologies. Ap roduct yield of 99 %w as achievedb yu sing Cu 2 O rhombicd odecahedra to catalyzet he hydroboration of phenylacetylene at 60 8Cfor 5h.T he rhombic dodecahedrah ave been shown to catalyze av ariety of substituted aryl alkynes, which demonstrates their potential as aversatile catalyst.

Overview of Regioselective and Stereoselective Catalytic Hydroboration of Alkynes

“…The 3d transition metals are earth‐abundant and demonstrate less toxic behavior, which makes them one of the prior choices for catalysis. In this regard, various first‐row transition metals are also used as efficient catalysts in syn ‐selective hydroboration, for instance, Ti, [48,49] Mn, [50] Fe, [51–58] Co, [59–61] Ni, [62] Cu, [63–77] and Zn [78] …”

“…Cu catalysts have contributed significantly to hydroboration of alkynes in a highly stereo‐ and regioselective manner [63–77] . It is worthy of mention that the β‐ or α‐selective borylation of aromatic substituted unsymmetrical internal alkynes (such as 32 or 34 ) was achieved by varying the borylating reagents.…”

Tuning Polarity of Cu-O Bond in Heterogeneous Cu Catalyst to Promote Additive-free Hydroboration of Alkynes

“…The more ionic Cu-O bond leads to the catalytic production of important compounds, vinylboronates, a versatile class of intermediates for construction of numerous valuable complex molecules. [20][21][22][23] For now, the heterogeneous catalytic hydroboration of alkynes presents a straightforward and cost-efficient approach to access these vinylboronates [24][25][26][27][28][29][30] but generally suffering from the requirement of ligands or bases as additional additives, which results in higher costs and more waste in the reaction. In this work, a melamine-formaldehyde resin (MF) coating layer between Cu atoms and the ceria can decompose and disappear from the high temperature heat treatment, resulting in the more ionic Cu-O bond in the final catalyst (denoted as Cu 1 -O(I)/CeO 2 ).…”

“…For now, the heterogeneous catalytic hydroboration of alkynes mainly depends on supported Cu catalysts. [24][25][26][27][28][29] These catalysts require ligands or bases as necessary additives because they can facilitate the formation of the crucial boryl copper species and thus promote the reaction pathway. [50][51][52] When these additives are absent, the hydroboration process is usually difficult to carry out smoothly.…”

In Situ Analysis of Growth Behaviors of Cu2O Nanocubes in Liquid Cell Transmission Electron Microscopy

“…Cuprous oxide (Cu 2 O) is a p-type semiconductor with a small bandgap of ∼2.2 eV that possesses unique chemical and physical properties . Because of its well-known merits, including being inexpensive, earth-abundant, and nontoxic, it has a wide range of applications. − For example, it can be used in catalysts, − gas sensors, − solar cells, batteries, chemical templates, and energy conversion . Various morphologies of Cu 2 O, including cubes, octahedra, , rhombic dodecahedra, , and hollow structures, − were synthesized in previous studies, and it was found that different morphologies had different properties.…”