Water-Dependent Selective Synthesis of Mono- or Bis-Selanyl Alkenes from Terminal Alkynes

Abstract

We described here an alternative method for the selective synthesis of mono‐ or bis‐selanyl alkenes. This method involves reactions of terminal alkynes with organylselenols, generated in situ by the reaction of diorganyl diselenides with H3PO2. These reactions proceeded efficiently at 90 °C under N2 atmosphere and are suitable to a range of diorganyl diselenides and terminal alkynes, both containing electron‐withdrawing and electron‐donating groups, affording the corresponding mono‐ or bis‐selanyl alkenes in good yields and selectively. When the reactions were performed using 5.0 equiv. of H3PO2 (0.5 mL; 50 wt% in H2O), mono‐selanyl alkenes were formed in good yields, whereas reactions carried out with additional H2O as the solvent (3.0 mL/mmol) provided bis‐selanyl alkenes in high yields. Additionally, the solvent/reducing agent system (H2O/H3PO2) could be recovered and directly reused for further reactions to synthesize bis‐selanyl alkenes.

“Green Is the Color”: An Update on Ecofriendly Aspects of Organoselenium Chemistry

“…With this method, the authors were able to flexibly obtain an array of densely functionalized vinylselenides (compounds 70 and 107) in yields ranging from fair to excellent, despite mixtures of E, Z, mono-and bis-selenylated compounds being obtained, mainly on the basis of whether the alkyne substrate was a terminal or internal one [154]. The same research group demonstrated that selectivity can be tuned toward the monoselenylated compounds, mostly as E-isomers, by running the reaction in a 50% wt solution of H3PO2 in THF, or toward the bis-substituted derivatives by removing the organic solvent [155] or using PEG-400 [156]. Vinyl selenides are valuable tools in organic chemistry [151][152][153] and examples of their synthesis in unconventional solvents have been reported recently.…”

“…With this method, the authors were able to flexibly obtain an array of densely functionalized vinylselenides (compounds 70 and 107) in yields ranging from fair to excellent, despite mixtures of E, Z, mono-and bis-selenylated compounds being obtained, mainly on the basis of whether the alkyne substrate was a terminal or internal one [154]. The same research group demonstrated that selectivity can be tuned toward the monoselenylated compounds, mostly as E-isomers, by running the reaction in a 50% wt solution of H3PO2 in THF, or toward the bis-substituted derivatives by removing the organic solvent [155] or using PEG-400 [156]. With this method, the authors were able to flexibly obtain an array of densely functionalized vinylselenides (compounds 70 and 107) in yields ranging from fair to excellent, despite mixtures of E, Z, mono-and bis-selenylated compounds being obtained, mainly on the basis of whether the alkyne substrate was a terminal or internal one [154].…”

Synthesis of Seleno‐Heterocycles via Electrophilic/Radical Cyclization of Alkyne Containing Heteroatoms

“…of H 3 PO 2 (0.5 mL; 50 wt% in H 2 O) afforded the mono-selanyl alkenes 321 in good yields, whereas reactions carried out with addi- tional H 2 O as the solvent (3.0 mL/mmol) afforded the bis-selanyl alkenes 322 in high yields (Scheme 102). [194][195] The synthesis of alkenyl diselenocyanate 324 has been developed via stereoselective difunctionalization of alkyne 323 with KSeCN at room temperature under mild and metal-free conditions by the simple use of PhI(OAc) 2 as the oxidant (Scheme 103). [196] The synthesis of Z-3-selenocyanatoacrylate 327 and analogues through green selenocyanation of activated alkyne 325 was successfully achieved by using lactic acid is shown in Scheme 104.…”

Water and Aqueous Mixtures as Convenient Alternative Media for Organoselenium Chemistry

“…Very recently it was reported by Alves et al that the solvent can also selectively direct the selenenylation of terminal alkynes toward the formation of mono-selanyl alkenes when the reaction is performed in solvent-free conditions, or bis-selanyl alkenes when the reaction is performed in water [63].…”

“…Finally, an aqueous NaOH solution has recently been used for the synthesis of spirocyclopropyl oxindoles through a domino Michael/intramolecular nucleophilic substitution sequence using different combinations of substituted vinyl selenones and enolizable oxindoles [65], as well as for the Very recently it was reported by Alves et al that the solvent can also selectively direct the selenenylation of terminal alkynes toward the formation of mono-selanyl alkenes when the reaction is performed in solvent-free conditions, or bis-selanyl alkenes when the reaction is performed in water [63].…”