Indium(I) Bromide-Mediated Regioselective Markovnikov Hydroselenation, Diselenation and Hydration of Terminal Alkynes with Diphenyldiselenide in Aqueous Media

Abstract

The indium(III) selenolate obtained from indium(I) bromide and diphenyldiselenide promotes, alternatively, the Markovnikov hydroselenation, diselenation or hydration of terminal alkynes, depending on the experimental conditions. For many years, the interest in indium chalcogenates was related to their use as precursors of semiconductors type InE (E = chalcogene). 1 Only recently, it was demonstrated that some of these compounds can, conveniently, be used as useful reagents in organic transformations (Scheme 1). IIn(EPh) 2 (E = Se, Te) promotes the hydrochalcogenation of 2-alkyn-1-ol derivatives, in non-aqueous media, with rigorous regio-, and stereochemical control; the products correspond to Markovnikov adducts resulting of an anti addition of the chalcogenol constituents across the triple bonds. 2 IIn(SePh) 2 promotes the ring-opening reaction of epoxydes to the corresponding bhydroxy selenides with rigorous regioselectivity; the nucleophile incorporation at the less hindered carbon atom was observed for alkyl-substituted epoxides, and at the benzylic carbon atom for aryl derivatives. 3 Further, IIn(SePh) 2 was used to prepare unsymmetrical selenides from organyl halides. 4 Scheme 1 Organic reactions promoted by indium chalcogenatesContinuing our studies on the applications of indium compounds in organic synthesis, we examine here the hydroselenation of unactivated alkynes with indium(III) selenolates in aqueous media. We envisaged this reaction on observing that the compounds XIn(SePh) 2 (X = Br, I), prepared from InX and PhSeSePh in THF, MeCN or CH 2 Cl 2 and X 2 InSePh, obtained from InX and PhSeX in THF or CH 2 Cl 2 , readily decompose under moisture. Therefore, we first examined the nature of this decomposition. To a freshly prepared solution of Br 2 InSePh in THF, under N 2 atmosphere, was added an equivalent amount of 2,2¢-dipyridyl followed by a 5-fold excess of water; the resulting solution was allowed to contact with air. This treatment resulted in the slow deposition of colorless crystals of [Br 2 InOH(bipy)] 2 ·4THF (Scheme 2). 5 Benzeneselenol could not be isolated, since it was completely oxidized to diphenyldiselenide by air.Scheme 2 Decomposition of Br 2 InSePh by moisture [Br 2 InOH(bipy)] 2 ·4THF was characterized by X-ray means. 6 The compound, in the solid state, is a centrosymmetric dimer. The dimerization occurs through the hydroxylic oxygen atom, leading to a planar In 2 O 2 fourmembered ring. Two bromine and one bidentate 2,2-dipyridyl ligands complete the hexacoordination at each metal center. The geometrical arrangement around the indium centers is a distorted octahedron guarding a cis-relationship between each pair of similar ligands. The THF molecules are loosely held in the lattice and do not show any interaction with the indium complex. IIn(EPh) 2 + R-Y R-EPh CH 2 Cl 2 (E = Se; Y = Cl, Br, I, R = alkyl, benzyl, allyl, etc.) H EPh OH R 2 R 3 (E = Se, Te; R 1 , R 2 , R 3 = alkyl and aryl) i ii iii SePh In Br Br H 2 O bipy 2 O In O In Br Br Br Br H H bipy bipy 2 InBr + 2 BrSePh THF O...

One‐Pot Indium Iodide Mediated Synthesis of Chiral β‐Seleno Amides and Selenocysteine Derivatives by Ring‐Opening Reaction of 2‐Oxazolines

“…Concerning the high stability of organic indium compounds in water relative to other metals, we evaluated the reaction in EtOH/H 2 O (2:1), but unfortunately the product was obtained in low yield (Table 1, Entry 6). Presumably under these conditions, the indium(III) selenolates are readily hydrolyzed to produce the corresponding selenol and indium(III) hydroxide 9b…”

Recent Advances in Indium-Promoted Organic Reactions

“…Thus, under reflux conditions, the terminal aliphatic alkynes 110 gave the methyl ketones 111 (Scheme 50). 165 The nucleophilic substitution of glycosyl bromides with indium(III) phenyl and butyl selenolates was found to constitute a convenient preparation of selenoglycosides. 166 first reduce the alkyl halide.…”

Unusual Influence of the Structures of Transition Metal Complexes on Catalytic C–S and C–Se Bond Formation Under Homogeneous and Heterogeneous Conditions

“…(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) so far been developed, including halogen substitution in vinyl halides, [5] preparation from olefins [6] and carbonyl [7] compounds, rearrangement of propargylic aryl chalcogenides, [8] selenodecarboxylation, [9] utilization of In, [10] Al, [11] Li, [12] Ti, [13] and Ga [14] reagents, and some other methods. [1] The best solution to the problem would be provided by addition reactions of element-hydrogen (E-H) and elementelement (E-E) bonds to easily available acetylenic hydrocarbons (E = S, Se).…”