Gold(I)-katalysierte diastereoselektive Hydroacylierung terminaler Alkine mit Glyoxalen

Preparation of Tremorine and Gemini Surfactant Precursors with Cationic Ethynyl-Bridged Digold Catalysts

Tremorine and precursors of gemini surfactants were synthesised in a one-pot, three-step, double-catalytic A³ coupling reaction and characterised by structural and spectroscopic methods. The cationic [Au^I (L1)]SbF₆ complex is a more active catalyst compared to neutral L2- and L3-Au^I bis(trifluoromethanesulfonyl)imidate complexes (L1, L2=Buchwald-type biaryl phosphane; L3=triphenylphosphine) in promoting the double A³ coupling of ethynyltrimethylsilane, secondary amines (cyclic, aliphatic, or aromatic) and formaldehyde. The solvent influences the catalytic performance by desilylation of silyl acetylene or deactivation of the catalyst by a halide anion. Acetylide-bridged cationic digold(I) L1 and L2 complexes were isolated and characterised by means of single-crystal X-ray structure analysis and their spectroscopic properties. Iodine in the acetylene reagent deactivates the Au^I catalyst by formation of the less active iodido-bridged cationic digold(I) L1 complex, which was fully characterised by single-crystal X-ray crystal structure analysis and spectroscopy. The nature of the phosphine ligand of the gold complexes used as catalyst affects the stability and activity of the formed cationic ethynyl-bridged Au^I₂ -L intermediates, isolation of which lends support to the proposed double A³ coupling mechanism.

Synthesis of 1,2-Dicarbonyl-3-enes by Hydroacylation of 1-Alkynes with Glyoxal Derivatives Using Metal-Organic Framework Cu/MOF-74 as Heterogeneous Catalyst

A crystalline copper-based metal-organic framework Cu/MOF-74 was synthesized, and used as an efficient heterogeneous catalyst for the synthesis of 1,2-dicarbonyl-3-enes by means of the hydroacylation of 1-alkynes with glyoxal derivatives in the presence of a base. Cu/MOF-74 was found to be more catalytically active for the synthesis of 1,2-dicarbonyl-3-enes than other MOFs including Cu₂ (BDC)₂ (DABCO), Cu₃ (BTC)₂ , Cu(BDC), Cu₂ (NDC)₂ (DABCO), Cu₄ I₄ (DABCO)₂ , Ni-MOF-74, Zn-MOF-74, Fe₃ O(BDC)₃ , In(OH)(BDC), and Zr₆ O₄ (OH)₄ (BDC)₆ . Cu/MOF-74 also exhibited better performance than other homogeneous copper catalysts, including Cu(OAc)₂ , Cu(NO₃ )₂ , CuI, CuBr, CuCl, CuCl₂ , and CuBr₂ . The Cu/MOF catalyst was able to be recovered and reused several times without a significant degradation in catalytic activity. To the best of our knowledge, the formation of 1,2-dicarbonyl-3-enes has not previously been carried out under heterogeneous catalysis conditions.

Splitting a Substrate into Three Parts: Gold-Catalyzed Nitrogenation of Alkynes by C-C and C≡C Bond Cleavage

A gold-catalyzed nitrogenation of alkynes for the synthesis of carbamides and amino tetrazoles through C-C and C≡C bond cleavages is described. A diverse set of functionalized carbamide and amino tetrazole derivatives were selectively constructed under mild conditions. The chemoselectivity can be easily switched by the selection of the acid additives. The reaction is characterized by its broad substrate scope, direct construction of high value products, easy operation under air, and mild conditions at room temperature. This chemistry provides a way to transform alkynes by splitting the substrate into three parts.