Refernces
10.1016/j.tetlet.2008.05.037
The study presents a rational design of bis(thiourea) cocatalysts to accelerate the Morita–Baylis–Hillman (MBH) reaction, a C–C bond forming reaction known for its sluggishness. By applying electronic structure calculations, the researchers identified key transition states and designed catalysts that could stabilize these states through hydrogen bond recognition of both nucleophile and electrophile. The cocatalysts were synthesized and tested, demonstrating significant acceleration of the MBH reaction between cyclohexenone and 4-fluorobenzaldehyde. The study shows that the designed cocatalysts, particularly one with an o-xylyl bridge, were much more effective than the previously reported bis(thiourea) cocatalyst, nearly tripling the reaction rate. The findings underscore the potential of computational methods in designing organic catalysts that utilize hydrogen bonding for enhanced reactivity.
10.1021/acs.jafc.9b00837
This study focuses on the development of chitinase inhibitors as a potential strategy for pest control, specifically targeting the chitinase enzyme (Of ChtI) from the Asian corn borer (Ostrinia furnacalis), which is crucial for the insect's molting process. The researchers utilized a pocket-based lead optimization strategy to synthesize and evaluate a series of compounds based on a 4,5,6,7-tetrahydrobenzo[b]thiophene-3-carboxylate scaffold. The lead compound 1 was optimized by introducing various nonpolar groups at the 6-position, resulting in compound 8, which exhibited the most promising inhibitory activity with a K value of 0.71 μM. The study combines computational modeling, molecular docking, and experimental bioassays to investigate the structure-activity relationships of these compounds, providing valuable insights for the design of more effective chitinase inhibitors as green pesticides.
10.1016/S0040-4020(01)97399-5
The research focuses on the cycloaddition reactions of sulfonylisothiocyanates with α,β-disubstituted enamines. The purpose of the study was to investigate the formation of cycloadducts and the corresponding dipoles, with a particular emphasis on understanding the structural changes these compounds undergo in different solvents and the factors influencing these transformations. The conclusions drawn from the study indicate that the formation of cycloadducts, rather than dipoles, can be attributed to steric effects, and that the structure of the adducts in solution is significantly influenced by solvent polarity. The researchers also observed a rapid equilibrium between the ring and dipole forms of the compounds, with the rate of conversion being fast compared to the NMR time scale. Key chemicals used in the process include sulfonylisothiocyanates, enamines, tosylisocyanates, and various organic solvents such as CDCl3, CD3CN, and liquid SO2, as well as perchloric acid and acetanhydride for protonation reactions.
10.3390/molecules21111443
The study focuses on the characterization of the O-methyltransferase enzyme JerF, which is involved in the late stages of jerangolid biosynthesis. JerF is unique for its ability to catalyze the formation of a non-aromatic, cyclic methylenolether, a reaction not previously characterized in other O-methyltransferases. The researchers successfully overexpressed JerF in E. coli and utilized cell-free extracts to conduct bioconversion experiments. They also chemically synthesized a range of substrate surrogates to evaluate JerF's catalytic activity and substrate tolerance. The results revealed that JerF has a broad substrate tolerance and high regioselectivity, making it a promising candidate for chemoenzymatic synthesis, particularly for the modification of natural products containing a 4-methoxy-5,6-dihydro-2H-pyran-2-one moiety. The study also highlighted the potential of JerF in introducing specific methylation patterns and its use in biorthogonal coupling reactions, such as click chemistry, for site-specific labeling of biomolecules like DNA, RNA, or proteins.
10.1016/S0040-4020(01)87537-2
The research focuses on the reactivity of lithium nitronate derived from 2-phenyl nitroethane when it reacts with acetic anhydride and acetyl chloride, leading to the formation of an intermediate nitrile oxide. The study aims to determine whether this intermediate acts as an electrophile or a dipolar species, depending on the protonating character of the medium. The conclusions drawn from the research suggest that the formation of nitrile oxide, likely through the loss of acetic acid from a mixed anhydride, is the most plausible reaction pathway and can account for the observed products. The chemicals used in this process include lithium nitronate, acetic anhydride, acetyl chloride, phenyl-2-nitroethane, and various other reagents and solvents such as ethyl ether, sodium hydroxide, and deuterated chloroform for the reactions and spectroscopic analysis.
10.1002/hlca.19500330323
This study focuses on the synthesis and analysis of various derivatives of p-aminosalicylic acid. The key chemicals involved include 2-nitro-p-toluidine, ethyl chloroformate, and sodium methoxide, which are used to produce 2-nitro-4-methoxytoluidine (I). This compound is then oxidized with potassium permanganate to give 2-nitro-4-carboxyaminobenzoic acid (II). Other derivatives synthesized include p-nitro-o-acetylsalicylic acid (III), ethyl p-acetylamidosalicylate (IV), and ethyl p-N-nicotinamidosalicylate (V), each of which is generated through specific reactions involving acetic anhydride, acetyl chloride, nicotinic chloride, and other reagents. The study also discusses esters of methionine and other specific amino acids, which react with crystalline chymotrypsin to form peptides, highlighting potential relevance to biological peptide synthesis. The study details the synthetic procedures and properties of the resulting compounds, and provides yields and melting points for each derivative, demonstrating chemical transformations and their analytical significance.
Xn,
Xi,
T
