Organoseleno-Catalyzed Synthesis of α,β-Unsaturated α′-Alkoxy Ketones from Allenes Enabled by Se···O Interactions

Abstract

α,β-Unsaturated α′-alkoxy ketones have been prepared under mild conditions from allenes using water as the oxygen source and without the necessity of metals. The organocatalytic oxygenation–rearrangement sequence displays an exquisite chemo-, stereo-, and site-selectivity as well as good functional group compatibility. DFT calculations suggest that stabilizing noncovalent Se···O interactions may be responsible for the observed reactivity.

Meyer–Schuster-Type Rearrangement of Propargylic Alcohols into α-Selenoenals and -enones with Diselenides

“…As a continuation of our studies on diselenide-mediated functionalization, we recently harnessed selenium-π-acid, which is electrophilic interactions between selenenium and π bond, to develop an efficient strategy for the preparation of oxazole acetals . Consequently, we speculated that in situ generated PhSeX electrophilic species should attack the carbon–carbon triple bond of propargylic alcohols, which would undergo seleno-rearrangement to deliver α-selenoenals and -enones. , Herein, we disclose the successful implementation of selenenylation/rearrangement of propargylic alcohols and present a broadly applicable protocol for the synthesis of multisubstituted α-selenoenals and -enones under neutral reaction conditions at room temperature.…”

Recent Advances in the Use of Diorganyl Diselenides as Versatile Catalysts

“…The synthesis of α’-alkoxy enone 42 starting from allenyl ether 41 was enabled by oxygenated rearrangement, which is promoted through an organoselenium-based π -acid-type catalysis [ 42 ]. In this method, 20 mol% of diphenyl diselenide A was utilised as the catalyst in a mixture of MeCN and THF as solvents at r.t.…”

Deciphering the Chameleonic Chemistry of Allenols: Breaking the Taboo of a Onetime Esoteric Functionality

“… 328 Selenium-based π-acid-type catalysis has been used for the preparation of α,β-unsaturated α′-alkoxy ketones from alkoxy-allenes through alkoxy migration. 329 …”

“…Nucleophilic attack of the isoxazole unit to the gold carbene carbon followed by a cascade azacyclization/rearrangement and aromatization would explain the observed indolizine compounds 536 and 537 (Scheme , bottom) . Selenium-based π-acid-type catalysis has been used for the preparation of α,β-unsaturated α′-alkoxy ketones from alkoxy-allenes through alkoxy migration …”