87705-34-8Relevant articles and documents
Rongalite promoted highly regioselective synthesis of β- hydroxytellurides
Sui, Dongsheng,Wu, Feifei,Xu, Qing,Yu, Xiaochun
experimental part, p. 288 - 290 (2011/10/07)
Ditellurides undergo facile cleavage on treatment with rongalite (sodium hydroxymethanesulfinate) to generate tellurium anions in situ, which undergo ring opening of epoxides in high regioselective manner. A simple, cost-effective method has been develope
Vertical and nonvertical participation by sulfur, selenium, and tellurium
White, Jonathan M.,Lambert, Joseph B.,Spiniello, Marisa,Jones, Scott A.,Gable, Robert W.
, p. 2799 - 2811 (2007/10/03)
The mechanism of stabilization of positive charge on carbon by sulfur, selenium, or tellurium at the: β-position has been investigated kinetically, by measurement of rate enhancements, and structurally, by variation of the bond strength to the leaving group. Stabilization can occur either nonvertically with formation of a bridged intermediate or vertically through hyperconjugation within an open carbocation. We observed large rate enhancements (105 for S, 106 for Se) in 97% aqueous trifluoroethanol with trifluoroacetate as the leaving group. These enhancements are consistent with either mechanism. Product structures also are consistent with either mechanism. Nine crystal structures revealed that the bond to the leaving group (C-O) is lengthened by the presence of S or Se at the β-position, in proportion to the basicity of the leaving group. This lengthening is not accompanied by angle distortions expected for the bridging mechanism. The crystallographic data support vertical (hyperconjugative) character along the reaction coordinate, more so for selenium than sulfur.
DOMINANT cis-DIACETOXYLATION OF ALKENES WITH TELLURIUM(IV) OXIDE AND LITHIUM BROMIDE IN ACETIC ACID
Uemura, Sakae,Ohe, Kouichi,Fukuzawa, Shin-Ichi,Patil, Suresh R.,Sugita, Nobuyuki
, p. 67 - 78 (2007/10/02)
Oxidation of alkenes with tellurium(IV) oxide and lithium bromide in acetic acid affords the corresponding α,β-diacetoxyalkanes in good yields after acetylation of the primary products with acetic anhydride/pyridine.From cyclic alkenes such as cyclopentene, cyclohexene, cycloheptene, and 1,4-cyclohexadiene, the cis-diacetate is obtained as almost the sole product.In the cases of linear cis alkenes such as cis-2-octene and cis-4-octene cis-stereochemistry is also preferred (cis/trans = 87-89/13-11), while the proportion of the cis-product is decreased in the cases of the corresponding trans-alkenes (cis/trans = 56-58/44-42).Transformation of a C-Te bond to a C-OAc bond under these reaction conditions is shown unambiguously by using β-chloroalkyltellurium(IV) trichlorides (TeCl4 adducts of alkenes) and β-oxyalkyl phenyl tellurides (oxytellurenylation products of alkenes), cis-diacetates being solely formed from the trans-tellurium compounds in a cyclohexyl system.One of the possible reaction patways for the oxidation is proposed which involves the acetoxy-, hydroxy-, and/or halogeno-tellurinylation of a double bond followed by an SN2 type acetolysis of the produced C-Te bond.
