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A reaction of dimethyl bicyclo[2.2.2]oct-5-ene-endo-2,endo-3-dicarboxylate with 1,3-benzо- thiazole-2- and 3-methoxycarbonylpyridine-2-sulfenyl chlorides leads to two types of heterocyclization products, which are formed through the ring closure by the oxygen atom of the carbоmethoxy group and/or by the nitrogen atom of the hetaryl fragment of the sulfenylating agent. The product ratio is affected by the medium nature and structural features of sulfenyl chlorides.

Bis(4,6-dimethylpyrimidin-2-yl) diselenide, a new representative of dihetaryl diselenides, was obtained by successively treating selenourea with hydrochloric acid, acetylacetone, potassium hydroxide, and the system iodine—potassium iodide. The unusual planar trans-conformation of this compound (X-ray diffraction data) is stabilized by intramolecular attractive nonvalent Se…N interactions (Se…N, 2.926(1) A) and stacking of the π-systems of the aromatic heterocycles (the centers of the pyrimidine rings are spaced apart at 3.365(2) A). The energy parameters of the factors that make the molecular structure flattened were estimated by quantum chemical DFT calculations.

A reaction of 2-chloro-4,6-dimethylpyrimidine with sodium ditelluride in DMF afforded bis(4,6-dimethylpyrimidin-2-yl) ditelluride, a new representative of dihetaryl ditellurides. An X-ray diffraction study revealed an unusual planar trans-conformation of this compound, which is stabilized by both intramolecular attractive non-valent Te...N interactions (3.082(2) A) and π-stacking of the aromatic heterocycles (the centers of the pyrimidine rings are disposed at 3.421(3) ). The energy parameters of the factors that make the molecular structure flattened were estimated by quantum chemical DFT calculations.

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