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Reactions of trimethylsilyl azide with 3-trimethylsilyl-2-propynal and 2-propynal were studied. X-Ray analysis of the molecular structure of 4-trimethylsilyl-1H-1,2,3-triazole-5-carbaldehyde showed that the carbonyl group appears in the s-cis conformation with respect to the double C=C bond in the heteroring. The effect of the temperature and polarity of the medium on the ability of 1H-1,2,3-triazole-5-carbaldehyde to undergo dimerization to tricyclic bis-hemiaminals was examined by IR and 1 H NMR spectroscopy.

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Organo-silicon compounds S 0060Interaction of Heteroatom-Containing Propynals with S-, N-Binucleophiles. -Reactions of α-siliconand α-germanium-containing aldehydes (I) with primary amino compounds [(II), (V) and (VII)] proceed chemoselectively at the aldehyde group. In the case of 2-aminoethanethiol (II), the ratio of tautomers, 1,3-thiazolidine (III) and azomethine (IV), depends significantly on the nature of the heteroatom, the presence of a catalyst, and the use of microwave activation. -(DEMINA, M. M.; NOVOPASHIN, P. S.; KON'KOVA, T. V.; SARAPULOVA, G. I.; AFONIN, A. V.; MEDVEDEVA, A. S.; Chem. Heterocycl.

Reactions of α-silicon-and α-germanium-containing acetylenic aldehydes with 2-aminoethanethiol, ethylenediamine, and 2-amino-1,2,4-triazole proceed chemoselectively at the aldehyde group. The ratio of tautomers, azomethine and 1,3-thiazolidine, on interaction with 2-aminoethanethiol depends significantly on the nature of the heteroatom at the triple bond of the aldehyde, the presence of a catalyst, and the use of microwave activation.We have shown previously that the reaction of propynals R 3 MC≡CCHO (M = Si, Ge, C) with primary amines in the absence of catalyst proceeds chemoselectively at the aldehyde group with the formation of the corresponding azomethines [1]. The direction of the interaction with thiols depends on the nature of the heteroatom. On interacting trimethylsilylpropynal and thiols in the absence of solvent and catalyst at room temperature, depending on the reactant ratio, relatively stable acetylenic hemithials or thioacetals are isolated in quantitative yield. In the case of triethylgermylpropynal under comparable conditions (20°C, aldehyde-thiol, 1 : 2) adducts at the triple bond, the corresponding β-thiopropenals, are formed preferably [2]. Recently we discovered unexpectedly that, on interacting trimethylsilylpropynal with nucleophiles in the presence of catalysts, cascade heterocyclization reactions may take place. Under the action of p-toluenesulfonic acid trimethylsilylpropynal reacts with 2-aminopyridine on microwave (MW) activation with the formation of N (2'-pyridyl)-2-(trimethylsilylethynyl)-1,2-dihydropyridine-3,5-dicarbaldehyde [3], and under conditions of base catalysis (DABCO) undergoes trimerization into 4-(trimethylsilylethynyl)-4H-pyran-3,5-dicarbaldehyde [4].The interaction of hetero-containing propynals with bisheteronucleophiles has not been investigated up to the present time. The aim of the present work is the study of the reaction of trimethylsilyl-and triethylgermylpropynal 1a,b with certain N,N-and N,S-binucleophiles, in particular 2-aminoethanethiol, ethylenediamine, and 3-amino-1,2,4-triazole, and to search for conditions for the selective reaction process. The presence in the 2-aminoethanethiol molecule of two nucleophilic centers a priori affords the possibility of forming _______ * Dedicated to our teacher, Academician of the Russian Academy of Sciences M. G. Voronkov, in connection with his 85 th birthday __________________________________________________________________________________________