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The [3+2] cycloaddition reaction of mesityl propargyl sulfide with ethyl glyoxylate was found to occur by using tin(IV) chloride to give a 2,5-dihydrofuran derivative. On the other hand, when 3-silyl propargyl sulfides were used, allyl alcohols were obtained. In the case of propargyl sulfides possessing dimethyl groups at the α-position of the propargyl group, cycloaddition products were obtained even if a silyl group was present on the propargyl group. In addition, mesityl propargyl selenides also reacted with ethyl glyoxylate by using tin(IV) chloride to give the corresponding [3+2] cycloaddition products. [ABSTRACT FROM PUBLISHER]

The reaction of SnCl4with β-chlorovinyl aldehydes in anhydrous dichloromethane gave a series of octahedral complexes of the general formula SnCl4·2L (L = aldehyde). The adducts have been characterized in solution using multinuclear (1H,13C, and119Sn) NMR and IR spectroscopy. Solution NMR studies show that the complexes undergo rapid ligand dissociation at ambient temperature. Ligand exchange is slowed significantly at low temperature, such that, in most of the complexes, it is possible to identify both thecisandtransisomers with predominance of thecisform. The magnitude of the metal-ligand interaction was estimated on the basis of119Sn NMR chemical shifts and used to classify the aldehydes studied according to their Lewis basicity. [ABSTRACT FROM PUBLISHER]

Four octahedral complexes of the type SnCl4.2L [L = (R2N)3P(E): E = Se; R = Me(1), Et(2) and E = S; R = Me(3), Et(4)] have been studied in solution by multinuclear (31P, 77Se, and 119Sn) NMR spectroscopy. 31P and 77Se NMR data were informative of changes associated with complex formation. The solution structure of the complexes was confirmed by their 119Sn NMR spectra that showed two triplet features for each complex, attributed to a mixture of the expected cis and trans isomers. The triplet signal is due to the coupling with two equivalent phosphorus atoms, consistent with an octahedral geometry around the tin center. In addition, density functional theory (DFT)/B3LYP calculations have been carried out to support the interpretations of NMR data. The results are discussed and compared with those reported for related complexes. GRAPHICAL ABSTRACT [image omitted] [ABSTRACT FROM AUTHOR]