The research presents a novel method for C-C bond formation between tertiary amines and carbon nucleophiles using molecular iodine as a catalyst, molecular oxygen as the terminal oxidant, and visible light irradiation. The study explores cross-dehydrogenative coupling (CDC) reactions, which are advantageous as they do not require preactivation of precursors. The experiments involved using N-phenyl tetrahydroisoquinoline as a test substrate with nitromethane, and various iodine sources and solvents were tested to optimize the reaction conditions. The best results were obtained using acetonitrile (MeCN) as the solvent and iodine (I2) as the catalyst. The reaction was carried out under an oxygen balloon, with a 22 W fluorescent lamp providing the visible light irradiation. Control experiments confirmed the necessity of molecular iodine, molecular oxygen, and light for the reaction to proceed. The scope of the reaction was further demonstrated with different substrates and carbon nucleophiles, yielding products such as aza-Henry and Mannich products. The reaction mechanism was also investigated, suggesting the formation of iminium ions by oxidation of tertiary amines, followed by acid-promoted addition of the carbon nucleophile.
The research focuses on the development of a novel C2-symmetric Schiff-base ligand derived from tridentate-Schiff-base, which is applied to the asymmetric Michael addition of nitroalkanes to 2-enoyl-pyridine N-oxides. This ligand, when combined with scandium(III) or copper(II) complexes, catalyzes the reaction with unprecedented levels of diastereoselectivity and enantioselectivity. The study explores the reaction using various nitroalkanes and 2-enoyl-pyridine N-oxides, achieving high yields and stereoselectivities. The researchers also demonstrate the synthetic utility of this method by converting the optically active adduct to a biologically active dihydro-2H-pyrrol 4a, an analogue of nicotine. Analyses include the determination of yields, enantiomeric excess (ee) by HPLC on a chiral stationary phase, and diastereomeric ratios (d.r.) by 1H NMR spectroscopy. The research also investigates the reaction mechanism, revealing a negative nonlinear effect in the catalysis by scandium, and proposes a transition-state model based on spectroscopic experiments and product configuration analysis.
The research presents an in-depth study on the application of two-directional synthesis in diversity-oriented synthesis (DOS), focusing on the rapid construction of complex molecular architectures from simple starting materials, particularly for the synthesis of alkaloid scaffolds. The experiments involved the synthesis of linear precursors, such as N-Boc-aminoalkenes containing α,β-unsaturated ester groups, which were then subjected to intramolecular pairing reactions under various Lewis acid conditions to form bicyclic and tricyclic scaffolds. Reactants included compounds like nitromethane and tris(hydroxymethyl)aminomethane (Tris), and analyses utilized techniques such as NMR spectroscopy, X-ray crystallography, and IR spectroscopy to confirm the structures and stereochemistry of the synthesized compounds. The study also explored the total synthesis of myrrhine and the potential of different substrates like nitromethane and Tris in DOS, demonstrating the versatility and efficiency of two-directional synthesis in generating molecular diversity.
The research focuses on the tautomeric preferences of 2-phenylhydrazones of 1,3-diphenyl-1,2,3-trione in chloroform solution, as detected by 15N NMR chemical shifts. The study aims to understand whether the substituent in the phenylhydrazone moiety influences the tautomeric preference and the transmission of the substituent effect within the molecules. Experiments involved the synthesis of compounds through the coupling of benzenediazonium ion to 1,3-diphenyl-1,3-propanedione, followed by purification via recrystallization from ethanol. The synthesized compounds were then analyzed using 1H, 13C, and 15N NMR spectroscopy, with chemical shifts referenced to tetramethylsilane (TMS) and nitromethane. Additionally, ab initio calculations at the HF/B3LYP level of theory with GIAO-HF/DFT method were conducted to calculate the chemical shifts of carbon atoms, and X-ray crystallography was used to detect the tautomer in the crystal state. The study found that the ketohydrazone tautomer is significantly favored over its proton-transfer products, and this tautomer was also detected in the crystalline state, indicating that the additional carbonyl group or substituent does not affect the tautomeric and configurational preferences.
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13813-25-7
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141-32-2
3959-07-7
128-37-0
7803-57-8
106-96-7
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