10.1080/15257770500544545
The research focuses on the microwave-assisted organic synthesis (MAOS) of 3-(D-gluco-pentitol-1-yl)-1H-1,2,4-triazole, a compound of interest in medicinal chemistry due to its pharmacological activities. The study aims to accelerate the synthesis of seco C-nucleosides of 1,2,4-triazole using microwave irradiation, which is reported to provide higher yields and purities compared to traditional synthetic methods. The chemicals used in the process include D-glucono- and D-galactono-1,5-lactones, thiocarbohydrazide, p-nitrobenzaldehyde, ethyl chloroacetate, and various reagents for subsequent reactions such as acetic anhydride, sodium acetate, and ammonium hydroxide. The conclusions of the research indicate that microwave irradiation significantly accelerates the synthesis of the target compounds, improving yields and reducing reaction times, thus demonstrating the effectiveness of MAOS in the synthesis of these potentially medicinally important compounds.
10.1246/bcsj.54.1844
The study investigates the synthesis of oxazolidines, thiazolidines, and 5,6,7,8-tetrahydro-1H,3H-pyrrolo[1,2-c]oxazole (or thiazole)-1,3-diones from β-hydroxy- or β-mercapto-α-amino acid esters. Aromatic aldehydes such as benzaldehyde, p-anisaldehyde, p-chlorobenzaldehyde, and p-nitrobenzaldehyde are used to react with amino acid ethyl esters like L-serine, 3-phenyl-DL-serine, L-threonine, or L-cysteine to form oxazolidines or thiazolidines. These compounds can then be converted into oxazoles and thiazoles through dehydrogenation using N-bromosuccinimide. Acetylation of oxazolidines and thiazolidines leads to N-acetylderivatives, which can undergo cyclization in the presence of anhydrous ZnCl? to form the tetrahydro-pyrrolo[1,2-c]oxazole (or thiazole)-1,3-diones. The study also explores the interaction of oxazolidines and thiazolidines with p-nitrobenzaldehyde and piperidine to form Mannich bases. The IR spectra of the synthesized compounds are analyzed, showing characteristic shifts and absorptions related to functional groups such as the ester group and the oxazole or thiazole ring.
10.1039/c0ob00644k
The study presents an efficient one-pot synthesis method for highly functional alkenes through a phosphine-catalyzed tandem three-component reaction involving aldehydes, alkyl vinyl ketones, and amides. The process utilizes either EtPPh2 or PPh3 as catalysts and achieves high yields (68–99%) with excellent stereoselectivity (E/Z ratios up to 98:2) within a total reaction time of 3 to 29.5 hours. The study also explores the scope of the reaction with various aryl- and heteroaryl-substituted aldehydes, amides, and alkyl vinyl ketones, demonstrating the versatility and practicality of the method. The reaction mechanism is proposed to involve a Morita–Baylis–Hillman reaction followed by a Michael addition, leading to the formation of the desired alkenes. The mild reaction conditions and the high atom economy of the process make it a valuable addition to organic synthesis.
10.1007/BF00480846
The research focuses on the synthesis and study of the reactivities of hydroxylaminothia(imida)zolidine-2-thiones(ones) and their reactions with 4-nitrobenzaldehyde. The purpose of the study was to investigate the formation of stable nitrones and the potential rearrangement of these compounds under different reaction conditions. The researchers found that 5-hydroxylaminothiazolidine-2-thiones react with the aldehyde to form stable nitrones, while isomeric 4-hydroxylaminothiazolidine-2-thiones and 4-hydroxylaminoimidazolidin-2-one can undergo rearrangement to E- or Z-O-substituted 4-nitrobenzaldoximes, depending on the structure and reaction conditions. Key chemicals used in the process include 4-nitrobenzaldehyde, various hydroxylaminothiazolidine-2-thiones and hydroxylaminoimidazolidin-2-ones, 4-toluenesulfonic acid (TSA) as a catalyst, and sodium borohydride for reduction reactions. The study concluded that nitrones V and VI, unlike isomeric compounds I and II, undergo hydrolysis to corresponding 4-hydroxy derivatives and E-4-nitrobenzaldoxime under acid-catalysis conditions, and that the rearrangement of these compounds can lead to different oxime structures based on steric hindrance and other factors.
10.1016/j.tetlet.2013.07.053
N. Nageswara Rao and H. M. Meshram describe a highly efficient method for functionalization of sp3 C–H bonds of methylazaarenes using water as solvent under microwave irradiation followed by nucleophilic addition with aromatic aldehydes. 4-Nitrobenzaldehyde (2k) reacts with methylazaarenes to give the desired products. It was found that water acts as both solvent and phase transfer catalyst under microwave irradiation, significantly improving the efficiency of the reaction. The optimal reaction conditions were determined to be 105°C and reaction time of 18–40 min. The scope of the reaction was explored with various aromatic aldehydes and 2-alkylazaarenes, and the results showed good tolerance to different substituents and good product yields. The method is superior to previous methods in terms of mild conditions, high efficiency, and the use of environmentally friendly water as solvent.
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