10.1007/s11172-005-0385-2
The research focuses on the synthesis of 2-alkylthio-6-methylpyridine-3-carbaldehydes, which are significant as building blocks in heterocyclic synthesis. The study aimed to develop methods for preparing these aldehydes using sodium bis(2-methoxyethoxy)aluminum hydride (BMA) and its complex with piperidine (BMAP) as reducing agents. The researchers found that the use of BMA on specific substrates yielded a mixture of products, with aldehydes being formed but in low yields and with byproducts. A more effective route to the desired aldehydes was identified through the reaction of BMAP with the corresponding esters rather than nitriles. The synthesized aldehydes were then subjected to condensation reactions with malononitrile and methyl cyanoacetate, resulting in the formation of hetarylidene derivatives. Key chemicals used in the process include 2-alkylthio-3-cyano-6-methylpyridines, their esters, malononitrile, methyl cyanoacetate, and the reducing agents BMA and BMAP. The study concluded that while BMA and BMAP can be used to synthesize the target aldehydes, the yields are low and side products are formed; however, using BMAP with esters instead of nitriles improves the yield and reduces side reactions.
10.1002/hlca.200900319
The research aims to develop efficient one-pot synthesis methods for 2-aminopyrimidinones and their piperidinium salts, which are significant due to their biological activities and potential applications in nanotechnology and crystal engineering. The study introduces a three-component reaction involving benzaldehyde derivatives, methyl cyanoacetate, and guanidinium carbonate to produce 2-amino-4-aryl-1,6-dihydro-6-oxopyrimidine-5-carbonitriles. Additionally, a four-component reaction with benzaldehyde derivatives, methyl cyanoacetate, guanidinium hydrochloride, and piperidine yields piperidinium salts of pyrimidinones. The synthesized compounds were characterized using NMR spectroscopy, mass spectrometry, and X-ray crystallography, confirming their structures and self-assembly through H-bonding. The research concludes that these one-pot methods offer high bond-forming efficiency, atom economy, and the use of simple, readily available starting materials, making them advantageous for the synthesis of these compounds.
10.1002/hc.10106
The study focuses on the synthesis and chemical behavior of 5-chloro-1,2,4-thiadiazol-2-ium chlorides (salts 3), which are useful precursors to a variety of 6aλ4-thiapentalene systems. These salts were obtained by treating formimidoyl isothiocyanates (1) with an excess of methanesulfenyl chloride. The salts exhibited interesting chemical behavior towards several nitrogen and carbon nucleophiles, leading to the formation of diverse polyheterapentalene systems. Key chemicals used in the study include isothioureas, acetamide, p-toluidine, phenyl isothiocyanate, and active methylene compounds like methyl cyanoacetate and dimethyl malonate. These reagents served to displace the 5-chlorine atom of the salts, leading to the formation of various heterocyclic compounds such as 1H,6H-6aλ4-thia-1,3,4,6-tetraazapentalenes (7), 6H-6aλ4-thia-1-oxa-3,4,6-triazapentalene (9), and other thiapentalene derivatives. The study utilized IR and NMR spectroscopic data for structural assignments and received additional support from X-ray analysis of substrate 16a. The purpose of these chemicals was to explore the reactivity of the thiadiazolium salts and to synthesize new hypervalent sulfur compounds through nucleophilic substitution reactions.
