Synthesis of a stable selenoaldehyde by self-catalyzed thermal dehydration of a primary-alkyl-substituted selenenic acid

Shohei Sase; Ryo Kakimoto; Kei Goto

doi:10.1002/anie.201409485

Synthesis of a stable selenoaldehyde by self-catalyzed thermal dehydration of a primary-alkyl-substituted selenenic acid

Angew Chem Int Ed Engl. 2015 Jan 12;54(3):901-4. doi: 10.1002/anie.201409485. Epub 2014 Nov 19.

Authors

Shohei Sase¹, Ryo Kakimoto, Kei Goto

Affiliation

¹ Department of Chemistry, Graduate School of Science and Engineering, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8551 (Japan).

PMID: 25411119
DOI: 10.1002/anie.201409485

Abstract

The unprecedented dehydration of a selenenic acid (RCH2SeOH) to a selenoaldehyde (RCH=Se) has been demonstrated. A primary-alkyl-substituted selenenic acid was synthesized for the first time by taking advantage of a bulky cavity-shaped substituent. Upon heating in solution, the selenenic acid underwent thermal dehydration to produce a stable selenoaldehyde, which was isolated as stable crystals and crystallographically characterized. Investigation of the reaction mechanism revealed that this β dehydration reaction involves two processes, both of which reflect the characteristics of a selenenic acid: 1) dehydrative condensation of two molecules of selenenic acid to generate a selenoseleninate intermediate [RCH2SeSe(O)CH2R], an isomer of a selenenic anhydride, and 2) subsequent β elimination of the selenenic acid from this intermediate to form a C=Se double bond, which establishes the self-catalyzed β dehydration of the selenenic acid.

Keywords: protecting groups; reaction mechanisms; reactive intermediates; selenium; structure elucidation.