A Regioselective Synthesis of Novel Functionalized Organochalcogen Compounds by Chalcogenocyclofunctionalization Reactions Based on Chalcogen Halides and Natural Products

The regioselective synthesis of novel functionalized condensed organochalcogen compounds by chalcogenocyclofunctionalization reactions based on chalcogen halides and the natural products thymol and carvacrol has been developed. The reactions of selenium dibromide with allyl thymol and allyl carvacrol proceeded in methylene chloride at room temperature in the presence of NaHCO₃ affording bis[(7-isopropyl-4-methyl-2,3-dihydro-1-benzofuran-2-yl)methyl] and bis[(4-isopropyl-7-methyl-2,3-dihydro-1-benzofuran-2-yl)methyl] selenides in 90–92% yield. Similar sulfides were obtained in 70–72% yields by the reaction of sulfur dichloride in chloroform under reflux. Trihalotellanes containing the same organic moieties were synthesized from allyl thymol, allyl carvacrol and tellurium tetrachloride or tetrabromide in quantitative yields. Corresponding functionalized ditellurides were prepared in 91–92% yields by the reduction of the trichlorotellanes with sodium metabisulfite in two-phase solvent system. The comparison of reactivity of sulfur, selenium and tellurium halides in chalcogenocyclofunctionalization and distinguishing features of each reaction were discussed.     

Dipropadienyl telluride

Russian Chemical Bulletin -     

Reactions of selenium dichloride and dibromide with diallyl telluride

Russian Journal of General Chemistry -     

Regio- and stereoselective addition of tellurium tetrachloride to methyl propargyl ether

Reaction of tellurium tetrachloride with methyl propargyl ether proceeds regio- and stereoselectively to afford a product of anti-addition against the Markovnikoff’s rule in quantitative yield. The obtained compound was reduced by sodium metabisulfite into E,E-bis(3-methoxy-1-chloroprop-1-en-2-yl)ditellane.     

Regioselective synthesis of functional tellanes from tellurium tetrahalides and 1-octene

Proceeding from TeCl₄ and 1-octene a regioselective method was developed of the synthesis of trichloro(2-chlorooctyl)tellane. At adding methanol to this compound chlorine was easily replaced at room temperature by a methoxy group affording trichloro(2-methoxyoctyl)tellane. The reaction of TeBr₄ with 1-octene in methanol resulted in tribromo(2-methoxyoctyl)tellane. A reduction of trichloro- and tribromo(2-methoxyoctyl)tellanes occurs the most selectively in the system NaBH4–water–THF giving 1,2-bis(2-methoxyoctyl)ditellane. The reactions are characterized by a high selectivity and quantitative yields of the products.     

Synthesis of Fused Compounds on the Basis of Chalcogen Chlorides and 2-Allylphenols

Efficient methods have been developed for regioselective synthesis of new organochalcogen compounds containing 2,3-dihydro-1-benzofuran-2-ylmethyl and 7-methyl-2,3-dihydro-1-benzofuran-2-ylmethyl substituents by reactions of selenium and sulfur dichlorides and tellurium tetrachloride with 2-allylphenol and 2-allyl-6-methylphenol.