Selenobenzoate, trimethylsilyl

Primary selenoamides are prepared by reaction of nitriles with appropriate selenating reagent, such as phosphorus (V) selenide (P2Se5), hydrogen selenide (H2Se), Al2Se3, NaSeH, trw(trimethylsilyl)monoselenophosphate or potassium selenobenzoate (Scheme 81).248 252... 

P2Se5, H2Se, AI2Se3, NaSeH, tris(trimethylsilyl)monoselenophosphate or potassium selenobenzoate. 

Although alkylation of potassium selenobenzoate with alkyl halides led to the formation of selenol esters via 5e-alkylation, as described in Section 2,6.2.1.1 (equation 9), the reaction of (66 equation 26) with trimethylsilyl chloride proceeded through 0-silylation to give trimethylsilyl selenobenzoate (67) in 68% yield. The driving force of the reaction may be due to the strong affinity of silicon for oxygen. 

The disparity of O and Se bases is illustrated in the esterification of potassium selenobenzoate (38). Thus, the 0-trimethylsilyl esters are produced on reaction with Me3SiCl, although compounds containing C=Se bonds are very unstable. On the other hand, the salt reacts with trimethylmetal chlorides of more polarizable elements to furnish the seleno esters. The trimethylsilyl ester is sensitive to moisture owing to the presence of a hard Si center. The stannoselenyl and germanoselenyl esters are quite stable toward hard bases. 

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