On the Role of Triethyl Borate in the Reduction of Elemental Selenium, Diselenide Dianions, Sodium Decyl Diselenolate, and Didecyl Diselenide with Sodium Borohydride

Abstract

Addition of triethyl borate to disodium diselenide or to sodium decyl diselenolate allows their reduction with sodium borohydride which otherwise does not take place.

Key words

selenium - reduction - sodium borohydride

References

• 1 Krief A. Dumont W. Trabelsi M. Derock M. Synlett  2004,  1751 
• 2 Krief A. Derock M. Synlett  2005,  in press 
• 3a

  Disodium diselenide has been prepared, as already described as a brownish solution, from elemental selenium and either NaH in DMF (1 equiv each, 70 °C, 2 h) [3a] or sodium in liquid NH₃ (1 equiv each) [3b] and replacement of the NH₃ by DMF.

• 3b Krief A. Derock M. Tetrahedron Lett.  2002,  43:  3083 
• 3c Brandsma L. Wijers HE. Recl. Trav. Chim. Pays-Bas  1963,  82:  68 
• 4a Organic Selenium Compounds: Their Chemistry and Biology   Klayman DL. Gunther WHH. John Wiley and Sons; Chichester: 1973. 
• 4b Sjöberg B. Herdevall S. Acta Chem. Scand.  1958,  12:  1347 
• 4c Günther WHH. Mautner HG. J. Med. Chem.  1964,  7:  229 
• 4d Sharpless KB. Lauer RF. J. Am. Chem. Soc.  1973,  95:  2697 
• 4e Sharpless KB. Lauer RF. Teranishi AY. J. Am. Chem. Soc.  1973,  95:  6137 
• 4f Krief A. Rémion J. Tetrahedron Lett.  1976,  1385 
• 4g Liotta D. Sunay U. Santiesteban H. Markiewick W. J. Org. Chem.  1981,  46:  2605 
• 4h Miyashita M. Hosshino M. Yoshikoshi A. Tetrahedron Lett.  1988,  29:  347 
• 5 We have reported^5a however, that n-butyllithium cleaves the Se-Se bond of lithium n-butyl diselenolate to produce 2 molar equiv of lithium n-butylselenolate. See: Krief A. Van Wemmel T. Redon M. Dumont W. Delmotte C. Angew. Chem. Int. Ed.  1999,  38:  2245 

6

During the course of this work we observed that triethyl borate is produced besides didecyl selenide on sequential reaction of elemental selenium, sodium borohydride, ethanol and decyl bromide (Equation [1] , entry a). It has been distilled, in quantitative yield, from the crude mixture and compared to an authentic sample purchased from the Sigma Aldrich Company. It was nevertheless impossible to distill it out of the medium before addition of decyl bromide although it was easy to remove the solvent (heating up to 120 °C) from the reaction mixture.