10.1021/op700222r
The research focuses on the development of an efficient synthetic route for the manufacture of N-[5-(3-Imidazol-1-yl-4methanesulfonyl-phenyl)-4-methyl-thiazol-2-yl]acetamide, a potent candidate for respiratory treatments, specifically aimed at asthma. The new synthesis route addresses toxicity and safety issues from the original process by utilizing a key Darzens condensation and α,β-epoxide rearrangement, enhancing the practicality, robustness, and streamlining of the manufacturing process. The experiments involved a series of chemical reactions, including SNAr reactions, Henry condensation, reduction of nitro compounds, and the formation of heterocyclic moieties. Reactants such as 3,4-difluorobenzaldehyde, sodium methylsulfinate, nitroethane, and various other reagents were used. The analyses included monitoring reaction temperatures, yields, purities, and the use of techniques like NMR spectroscopy and high-resolution mass spectrometry (HRMS) to characterize the intermediates and final products. The study also explored alternative solvent systems and conditions to improve the overall yield and safety of the process.
10.1016/S0040-4020(01)80911-X
The research focuses on the synthesis of N-arylsulfonyl nitroacetamides through a novel route involving the reaction of N-arylsulfonyl carbonimidodithioic acid dimethyl esters with nitroalkanes to generate I-alkylthio-I-aryl sulfonamido-2-nitroethylenes, which are then hydrolyzed to the desired nitroacetamides. Key chemicals involved in the research include N-arylsulfonyl carbonimidodithioic acid dimethyl esters (I), nitroalkanes such as nitromethane and nitroethane, anhydrous potassium carbonate, and mercuric chloride for the hydrolysis step. The study also investigates the solvent-dependent tautomerism observed in the nitroenamines 2a-d, noting that these compounds exhibit different tautomeric forms depending on the solvent used, with the imine form predominating in non-polar solvents and the enamine form in polar solvents. This work provides a general synthetic route for a wide variety of substituted nitroacetamides, which are otherwise challenging to synthesize using conventional methods.
10.1021/ja075653v
The research explores the development of a new class of urea-based organocatalysts with an N-sulfinyl substituent that serves both as an acidifying group and a chiral controlling element. The purpose of this study is to enhance the enantioselectivity in the aza-Henry reaction, which involves the addition of nitroalkanes to imines, by using these novel organocatalysts. The researchers synthesized various N-sulfinyl urea and thiourea catalysts and tested their performance in the aza-Henry reaction. Key chemicals used in the study include tert-butanesulfinamide, isocyanates, isothiocyanates, and nitroethane. The study concludes that N-sulfinyl ureas are effective organocatalysts, achieving high enantioselectivity and diastereoselectivity in the aza-Henry reaction with both aromatic and aliphatic N-Boc imines. Notably, this is the first report of enantioselective H-bonding-catalyzed additions to aliphatic N-Boc imines. The findings highlight the potential of N-sulfinyl ureas as versatile and efficient organocatalysts for asymmetric synthesis.
10.1002/chem.201502129
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.
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