Metal-Free Organocatalytic Oxidative Ugi Reaction Promoted by Hypervalent Iodine

We report here a novel IBX-promoted oxidative coupling of primary amines and its utilization to Ugi reaction. Advantageously, the reaction could be carried out in choline chloride urea as a natural deep eutectic solvent. A range of imines and bisamides from pseudo-four-component oxidative Ugi reaction could be synthesized under mild and metal-free conditions. Advantageously, the oxidant (IBX) and solvent could be recycled up to five times with only a slight loss in activity

Continuous Recycling of Homogeneous Pd/Cu Catalysts for Cross-Coupling Reactions

Given the importance of homogeneous catalysts recycling in organic chemistry, we have developed a unique microfluidic loop system for automated continuous recirculation of a soluble polymer supported metal catalyst for novel isocyanide cross-coupling reactions under thermomorphic multicomponent solvent (TMS) conditions. Our system provides an innovative approach for the chemical library synthesis of quinazolinone derivatives as well as an important intermediate of Merck’s LTD4 antagonist “Singulair” with efficient continuous homogeneous catalyst recycling

Electrochemical Post-Ugi Cyclization for the Synthesis of Highly Functionalized Spirolactams

The combination of the Ugi reaction and electro-organic synthesis can aid in the creation of novel heterocycles that have not been previously explored. In this study, a new strategy utilizing bis-amides from the Ugi reaction has been developed, which can produce C–S, C–Se, and C–CO functionalized five-membered spirolactams mediated by electricity under catalyst- and metal-free conditions. Notably, this approach can be applied using a microelectro-flow reactor (μ-EFR) for gram-scale synthesis. The described strategy can synthesize complex azaspiro-fused tricyclic scaffolds with high diastereo- and regioselectivity, highlighting its versatility and potential

Catalyst-Controlled Structural Divergence: Selective Intramolecular 7-<i>endo</i>-<i>dig</i> and 6-<i>exo</i>-<i>dig</i> Post-Ugi Cyclization for the Synthesis of Benzoxazepinones and Benzoxazinones

Metal catalyzed post-Ugi cyclization of bis-amides is reported in this study. Exposure of bis-amides to Pd­(II) catalyst triggered the formation of seven-membered benzoxazepinones. This investigation established that changing the catalyst to a Echavarren’s gold­(I) turned off cyclization to seven member ring and turned on 6-<i>exo</i>-<i>dig</i> annulations to afford family of six-membered benzoxazinones. To support the proposed mechanisms, quantum chemical based density functional theory calculations have been performed and validated. This novel method obtained molecular complexity up to four modular inputs and divergence of two different skeletons. 2D NMR spectroscopic techniques and single crystal X-ray diffraction established the proposed structures

One-Pot Defunctionalization of Lignin-Derived Compounds by Dual-Functional Pd₅₀Ag₅₀/Fe₃O₄/N-rGO Catalyst

Generation of hydrogen from renewable sources and its safe utilization for efficient one-pot upgrading of renewable biofuels are a challenge. Bimetallic PdAg catalyst supported on Fe₃O₄/nitrogen-doped reduced graphene oxide (N-rGO) were synthesized for hydrogen generation from formic acid with high TOF (497 h^–1 at 50 °C), and the hydrogen was subsequently utilized in situ for selective defunctionalization of lignin-derived chemicals with preserved aromatic nature at ambient pressure. Hydrodeoxygenation of aromatic aldehydes and ketones gave excellent yields (99% at 130 °C) with no use of additives. Furthermore, hydrogenolysis of β-O-4 and α-O-4 C–O model compounds produced only two products with high selectivity at 120 °C, which is an efficient and versatile one-pot platform for valorization of lignin biomass