Search

A reaction of 2-pyridinetellurium trichloride with unsaturated hydrocarbons leads to [1,3]tellurazolo[3,2-a]pyridinium-4 derivatives — the products of polar cycloaddition of tellurium-containing electrophile at the multiple bond.

In previous work [1–3], we synthesized a number of 2,3-dihydro[1,4]thiazino[2,3,4-ij]quinolinium-4 derivatives by the reaction of 8-quinolinesulfenyl chloride with alkenes. 8-Quinolineselanyl chloride (1) was obtained in a study of the feasibility of using this method for the synthesis of analogous selenium-nitrogencontaining heterocycles. The reactions of chloride 1 with indene 2 and styrene 3 were investigated. The reaction of selanyl chloride 1 with unsaturated compounds 2 and 3 in methylene chloride at 20°C leads to peri-fused systems 4 and 5 in 91 and 82% yield, respectively. H NMR spectroscopy showed that these reactions proceed regioand stereospecifically.

In recent years, we have developed a new approach to the synthesis of sulfur and nitrogen containing hetero cycles based on the polar cycloaddition of hetarenesulfenyl chlorides HetSCl to alkenes, dienes, and acetylenes accompanied by the ring closure through the nitrogen atom of the HetS fragment.1—6 In particular, it was found that the reactions of 2 pyridinesulfenyl chlorides con taining substituents in the pyridine moiety even with rather readily transformable bicyclic olefins, such as norbornene3 and norbornadiene,6 afford exclusively cycloaddition products with retention of the carbon skeleton of the starting unsaturated compound. With the aim of extend ing the synthetic scope of this approach, in the present study we examined the possibility of performing the tandem rearrangement—cyclization reaction with the use of readily available tetrafluorobenzobarrelene (1)7,8 as the model substrate. The choice of diene 1 was determined by the fact that its reactions with various electrophilic reagents, including sulfenylating agents, involve cascade skeletal rearrangements.8—10

The title compound, [SnCl(4)(C(10)H(8)N(2)Se)], was obtained by the reaction of 2,2'-dipyridyl diselenide with tin tetra-chloride. The Sn(IV) ion is coordinated by two N atoms [Sn-N = 2.266 (2) and 2.274 (2) Å] from the bis-(2-pyrid-yl)selenide ligand and four chloride anions [Sn-Cl = 2.3717 (6)-2.3939 (6) Å] in a distorted octa-hedral geometry. The central six-membered chelate ring has a boat conformation with the Se and Sn atoms deviating by 0.692 (3) and 0.855 (3) Å, respectively, from the mean plane through the remaining four ring atoms. The pyridine rings are inclined to each other by a dihedral angle of 49.62 (8)°. The crystal packing exhibits short inter-molecular Se⋯Cl contacts [3.5417 (7) and 3.5648 (7) Å], weak C-H⋯Cl hydrogen bonds and π-π stacking inter-actions between the pyridine rings with a centroid-centroid distance of 3.683 (3) Å.

The title compound, C7H5NSSe, is the product of the reaction of 2-chlorobenzothiazole with sodium hydroselenide. The molecule is almost planar (r.m.s. deviation = 0.018 Å) owing to the presence of the long chain of conjugated bonds (Se=C—N—C=C—C=C—C=C). The geometrical parameters correspond well to those of the analog N-methylbenzothiazole-2(3H)-selone, demonstrating that the S atom does not take a significant role in the electron delocalization within the molecule. In the crystal, molecules form centrosymmetric dimers by means of intermolecular N—H...Se hydrogen bonds. The dimers have a nonplanar ladder-like structure. Furthermore, the dimers are linked into ribbons propagating in [010] by weak attractive Se...S [3.7593 (4) Å] interactions.