Reactivity of aldehydes with semi-stabilised arsonium ylide anions: synthesis of terminal (e)-1,3-dienes |
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Authors: | Habrant Damien Stengel Bruno Meunier Stéphane Mioskowski Charles |
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Institution: | Laboratoire de Synthèse Bio-Organique, UMR 7175/LC1-CNRS, Faculté de Pharmacie, Université Louis Pasteur, 74 Route du Rhin, BP 24, 67401 Illkirch, France. |
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Abstract: | A study of the reactivity of semi-stabilised arsonium ylide anions in olefination reactions is presented. The different ylide anions were generated by the addition of nBuLi to various arsonium halide derivatives: Ph(2)As(R)R'](+)X(-), where R and R' are methyl, allyl, prenyl or benzyl groups. By using diallyldiphenylarsonium bromide (R=R'=allyl) an olefination protocol was optimised allowing the efficient transformation of aliphatic aldehydes into terminal 1,3-dienes with a high selectivity for the E isomer (E/Z ratios ranging from 90:10 to 97:3). The olefination reactions of aldehydes with dissymmetric arsonium halides (R not equal R') are very chemoselective; with arsonium ylide anions the benzyl moiety is more reactive than the allyl moiety which is much more reactive than prenyl and methyl groups. Based on the experimental results, a mechanism is proposed for the reaction. |
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Keywords: | 1 3‐dienes alkenes arsenic olefination ylide anions ylides |
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