Unsaturated five-membered selenium–germanium containing heterocycles based on the reactions of selenium di- and tetrahalides with diorganyl diethynyl germanes

Abstract

a b s t r a c tRegio-and stereoselective reactions of selenium dihalides with diorganyl diethynyl germanes in CHCl 3 afford in yields from preparative to quantitative the first representatives of a new class of selenium-germanium containing heterocycles -3,6-dihalogen-4,4-diorganyl-1,4-selenagermafulvenes. The reaction of selenium tetrachloride under the same conditions leads to the first representatives of a new class of selenium-germanium containing cyclopentene heterocycles -2-dichloromethyl-2,4-dichloro-3,3-diorganyl-1-selena-3-germacyclopentenes-4 as well as to the unknown 3,6,6-trichloro-4,4-dialkyl-1,4-selenagermafulvenes formed as a result of a spontaneous dehydrochlorination of the cyclopentene heterocycles. In a case of SeBr 4 the process of dehydrobromination is dominating. The structures of the heterocycles were proved by multinuclear ( 1 H, 13 C, 77 Se) spectroscopy and mass-spectrometry. In the 1 H NMR spectra of Z-isomers of 1,4-selenagermafulvenes a long-range spin-spin interaction between exo-and endocyclic olefinic protons through five bonds is revealed lacking in the E-isomers.

The reaction of selenium dichloride with divinyl sulfide

“…This reaction was performed with various diorganyl diethynyl silanes and germanes providing previously unknown 1-selena-4-silafulvenes and 4-germafulvenes [13][14][15][16][17][18].…”

“…Continuing our investigations of the addition of new reagents, selenium dichloride and dibromide, to unsaturated compounds with a goal to obtaining new selenium heterocycles [11][12][13][14][15][16][17][18][19], we have studied the reaction of selenium dichloride with divinyl sulfide.…”

Addition of selenium dibromide to divinyl sulfide: spontaneous rearrangement of 2,6-dibromo-1,4-thiaselenane to 5-bromo-2-bromomethyl-1,3-thiaselenolane

“…11,12 Various diorganyl diethynyl silanes and -germanes were involved in this reaction affording novel unsaturated 5-membered heterocycles, 1,4-selenasilafulvenes and 1,4-selenagermafulvenes. [13][14][15][16][17][18][19] Recently, the reaction of selenium dichloride with organolithium and organomagnesium reagents 20 and the addition of selenium dichloride to propargylic alcohols 21 have been reported.…”

“…In this work, we report studies on the addition reaction of selenium dibromide to divinyl sulfide. 25 The formation of 5-membered fulvenes rather then 6-membered heterocycles in our previous work [13][14][15][16][17][18][19] was suggested to be a result of the higher stability of 5-membered heterocycles. However, the reaction of selenium dibromide with divinyl sulfide in carbon tetrachloride at room temperature led to the 6-membered heterocyclic compound, 2,6-dibromo-1,4-thiaselenane (1), in near quantitative yield (Scheme 2).…”

First example of aromatic electrophilic substitution using selenium(II) chloride

“…While continuing our systematic studies on reactions of selenium dihalides [1,2,[4][5][6][7][8][9][10], we examined the reaction of selenium dichloride with methoxybenzene. The reaction occurred as aromatic replacement of hydrogen by the electrophile Se 2+ and afforded bis-(4-methoxyphenyl) selenide (I) in high yield (91%).…”