Efficient Preparation of α,α-Dialkyl-α-(phenylselanyl)acetates and α,β-Unsaturated Esters from the Corresponding α,α-Dialkyl-α-cyanoacetates by a Lithium Naphthalenide Induced Reductive Selenenylation Process

Abstract

An array of α,α-dialkyl-α-(phenylselanyl)acetates has been synthesized very efficiently from readily available α,α-dialkyl-α-cyanoacetates, by use of lithium naphthalenide induced reductive α-selenenylation as a key operation. Moreover, the selanyl esters thus generated in situ could be converted further, in a one-pot treatment with hydrogen peroxide and acetic acid, into the corresponding α,β-unsaturated esters in moderate to high yields. The C=C bond formation was highly regio- and/or diastereoselective in some cases.

Key words

nitriles - selenium - reductive selenenylation - lithium naphthalenide - α,β-unsaturated esters

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17

In theory, the reductive decyanation of α-cyano esters requires only two equivalents of lithium naphthalenide. In practice, however, we found that the use of less than five equivalents of lithium naphthalenide (e.g., 4 equiv) often resulted in incompletion of the reaction under the specified conditions (-45 °C, 25 min).