A novel strategy for the ESI-MS monitoring of reaction solutions involving the alternate use of permanently charge-tagged reagents has been used for comprehensive mass spectrometry monitoring of the multicomponent Hantzsch 1,4-dihydropyridine reaction. By placing a charge tag on either, or both, of the two key reactants, ion suppression effects for ESI were eliminated or minimized, and comprehensive detection of charge-tagged intermediates was achieved. The strategy allowed the trapping and characterization of the important intermediates in the mechanism for 1,4-dihydropyridine formation.

An efficient synthesis of 5‐organotellanyl‐1H‐1,2,3‐triazole compounds was accomplished through [3+2] cycloaddition reaction of organic azides and (organotellanyl)alkynes. Additionally, 5‐organotellanyl‐1H‐1,2,3‐triazoles were readily functionalized at the 5‐position by using a Sonogashira cross‐coupling reaction, leading to highly functionalised triazoles. The regiochemistry of the products was assessed by two‐dimensional NMR spectroscopic experiments and X‐ray crystallography.

Neste trabalho é descrita a habilidade do SnCl 2 .2H 2 O como catalisador na reação de Biginelli tricomponente. Uma variedade de aldeídos aromáticos mono-e dissubstituidos foi utilizada na condensação com acetoacetato de etila e uréia ou tiouréia. A reação foi efetuada em etanol ou acetonitrila como solventes em meio neutro e os resultados representam um melhoramento com relação ao procedimento clássico de Biginelli e uma vantagem com relação ao uso de FeCl 3 .6H 2 O, NiCl 2 .6H 2 O e CoCl 2 .6H 2 O que são utilizados juntamente com HCl como co-catalisador. A síntese das 3,4-diidropirimidinonas foi conseguida em bons rendimentos.The ability of SnCl 2 .2H 2 O as catalyst to promote the Biginelli three-component condensation reaction from a diversity of aromatic aldehydes, ethyl acetoacetate and urea or thiourea is described. The reaction was carried out in acetonitrile or ethanol as solvents in neutral media and represents an improvement of the classical Biginelli protocol and an advantage in comparison with FeCl 3 .6H 2 O, NiCl 2 .6H 2 O and CoCl 2 .6H 2 O which were used with HCl as co-catalyst. The synthesis of 3,4-dihydropyrimidinones was achieved in good to excelent yields.

Solutions of aza-Morita-Baylis-Hillman (aza-MBH) reactions were directly monitored by ESI(+)-MS(/MS) spectrometry to obtain information on their mechanism. A unique bis-sulfonamide intermediate was intercepted and characterized and, based on this novel species, a mechanism that rationalizes the uniqueness of aza-MBH reactions is proposed.

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