10.1080/00397911.2010.515361
The research presents a one-pot oxidation method for alanine and its ethyl ester using the mild oxidant 4′-methylazobenzene-2-sulfenyl bromide. The study focuses on the sulfenylation reaction of L-alanine and its ethyl ester with the oxidant in aqueous solution at room temperature, yielding sulfenimines that, upon acidic hydrolysis, produce ethanal and pyruvic acid, respectively. The experiments involved reacting L-alanine or its ethyl ester with the sulfenyl bromide in the presence of an acid scavenger, triethylamine, to form sulfenimines. These were then hydrolyzed in an acidic medium to obtain the carbonyl compounds. The reactants included L-alanine, its ethyl ester, 4′-methylazobenzene-2-sulfenyl bromide, and triethylamine. Analytical techniques used for characterization included infrared (IR) spectroscopy, proton nuclear magnetic resonance (1H NMR) spectroscopy, and elemental analysis. The products, acetaldehyde and pyruvic acid, were identified as their 2,4-dinitrophenylhydrazones after isolation.
10.1016/j.tetlet.2010.03.020
The research presents a new and milder procedure for the synthesis of N-protected α-aminoalkylphosphorylic compounds through the amidoalkylation of hydrophosphorylic compounds. The study involves the reaction of alkyl carbamates, aldehydes, and hydrophosphorylic compounds in acetic anhydride/acetyl chloride. The main reactants include dialkyl phosphites, diethylphosphinous acid, alkylphosphonous acids, methyl and ethyl carbamates, and aldehydes. The experiments led to the isolation of N,N-benzylidene- and N,N-alkylidenebiscarbamates as intermediates for the first time and provided evidence for a new reaction mechanism involving an Arbuzov-type reaction step. The analysis involved the use of 31P NMR spectroscopy to observe the formation of intermediate P–OAc derivatives and the monitoring of reaction yields under various conditions. The study also compared the effectiveness of different catalysts, such as trifluoroacetic acid (TFA) and p-toluenesulfonic acid (TSA), on the reaction yields. The results contribute to a better understanding of the amidoalkylation process and offer an improved method for synthesizing N-protected α-aminoalkylphosphorylic compounds, which are potential substrates in combinatorial peptide synthesis.
10.1021/jo9003635
The study focuses on asymmetric aldol-Tishchenko reactions involving enolizable aldehydes and ketones, using chiral BINOLTi(OtBu)2/cinchona alkaloids complexes as catalysts. The aim is to control the diastereoselectivity and enantioselectivity in these reactions, which are crucial for constructing defined adjacent stereogenic centers and are valuable for chiral economy. The researchers investigated how the configuration of substrates influences the reaction outcomes and explained their findings through transition state models and rate constants. The study utilized various enolizable aldehydes, ketones, and chiral catalysts to fine-tune the selectivity in aldol-Tishchenko reactions, ultimately providing access to defined configured stereotriads, stereotetrads, and stereopentads.
10.1021/jo981188w
The research focuses on the enantioselective synthesis of r,β,r′-trisubstituted cyclic ethers, which are structural motifs found in natural compounds with significant biological activities. The purpose of the study was to develop a synthetic strategy that controls the stereochemistry at the carbon atoms adjacent to the oxygen of the ether by employing a hetero Diels-Alder reaction between a monoactivated diene and a chiral aldehyde. The research concluded that the methodology was effective in preparing enantiomerically pure cis and trans cyclic ethers of varying sizes, demonstrating the versatility of the strategy based on the highly regioselective intramolecular alkylation of R-lithiosulfones with epoxides. Key chemicals used in the process include R-(+)-2,3-O-isopropylideneglyceraldehyde, monoactivated dienes, and various sulfone and silyl protecting groups, among others, to achieve the desired stereochemical control and functional group transformations.
10.1039/a607545b
The research aims to explore open-chain 1,3-stereocontrol in chemical reactions, focusing on the predictability of diastereoisomeric products formed during nucleophilic attacks on carbonyl groups adjacent to stereogenic centers. The study involves a series of reactions using a range of nucleophiles, including organolithium and organomagnesium reagents, with aldehydes and ketones that bear a stereogenic center carrying a silyl group. The researchers conducted numerous reactions to assess the relative stereochemistry of the products and attempted to identify a steric rule that could predict the major diastereoisomer in each reaction. The conclusions drawn from the research indicate that while a reliable rule for predicting the sense of 1,3-stereocontrol remains elusive, some generalizations can be made, particularly when R1 ≠ H ≠ Ph, and when M ≠ Ph, nucleophilic attack tends to occur in a specific sense (B). The study also highlights the influence of phenyl groups and the use of lithium reagents, which often led to inconsistent results. The chemicals used in the process include a variety of organometallic reagents, aldehydes, ketones, and silyl-protected compounds, among others.
10.1016/S0021-9517(03)00192-1
The research presented in the "Journal of Catalysis" focused on the aldol condensation of acetaldehyde and heptanal using hydrotalcite-type catalysts to produce 2-nonenal, a higher molecular weight aldehyde. The study explored the effects of various reaction parameters, including temperature, acetaldehyde to heptanal molar ratio, and the nature of the solvent (hexane, toluene, ethanol). The catalysts tested were MgO with strong Lewis basic sites, Mg(Al)O mixed oxides derived from hydrotalcite precursors with acid–base pairs of the Lewis type, and rehydrated Mg(Al)O mixed oxides with Br?nsted basic sites. The optimal reaction conditions were determined to be a temperature of 373 K, an acetaldehyde/heptanal molar ratio of 2/1, and an ethanol/reactants molar ratio of 5/1. The experiments involved the synthesis of Mg–Al hydrotalcite followed by its calcination at various temperatures to produce Mg(Al)O mixed oxides. The rehydrated form of these calcined materials was also tested. Characterization of the catalysts was performed using chemical analysis, XRD, BET specific surface area measurements, and basicity was studied by CO2 adsorption followed by calorimetry and gravimetry. The acidity was estimated from temperature-programmed desorption of NH3 (NH3-TPD). Catalytic tests were carried out in a stainless-steel autoclave, and the reaction products were analyzed by gas chromatography and mass spectrometry. The results provided insights into the influence of catalyst properties on the selectivity and conversion of reactants.
F+, 
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F, 
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F+:Highly flammable;
