Zirconium-Catalyzed Alkyne Carbo- and Cycloalumination Reactions in Stereoselective Preparation of 1-Alkenyl Selenides

Abstract

Supporting informationThe reagents were obtained from Sigma-Aldrich or Acros. Dichloromethane and hexane were distilled over P 2 O 5 . Organic diselenides were prepared by the reaction of elemental selenium with hydrazine hydrate and bromobenzene or bromoalkane under the action of sodium hydroxide solution in DMF [1]. The alkynyl selenides were prepared by the reaction of terminal alkynes with elemental selenium and bromoalkanes [2]. IR spectra were recorded on Bruker VE Vertex 70v spectrometer as liquid films or in Nujol and are reported in wavenumbers (cm -1 ).Nuclear magnetic resonance spectroscopy was performed on a Brucker Avance 400. The 1 H NMR spectra were recorded at 400 MHz and 13 C NMR spectra at 100 MHz in CDCl 3 . The chemical shifts are reported in ppm relative to tetramethylsilane (TMS) as the internal standard. The numbering of atoms in the 13 С and 1 H NMR spectra of the compounds A-F and 2a-f, 3b-e, 4a-e, 5b, 7a-f, 8ac is shown in Figures 1,2,3,4,5. Elemental analysis was performed using a Carlo-Erba CHN 1106 elemental analyser. Mass spectra were obtained on a Finnigan 4021 instrument. The yields were calculated from the isolated amount of 1-alkenyl selenides obtained from starting alkynes. All quantum-chemical calculations were performed using B3LYP/6-31G(d,p) basis set as implemented in Gaussian 09 software [3]. Preparation of alkynyl selenides A-F by the reaction of alkynyl lithium with elemental Se and bromoalkanes Figure 1The numbering of atoms in the 13 Сand 1 H-NMR spectra of the compounds A-F Butyl(hex-1-yn-1-yl)selenide (A)To a two-neck round-bottomed flask, under argon, containing a solution of hex-1yne (820 mg, 10 mmol) in THF (30 mL) at -78 o C was added to n-BuLi (4.0 mL of a 2.5M solution in hexane; 10 mmol). The reaction mixture was stirred for 30 min.After this the reaction was warmed to 0 o C and elemental selenium (800 mg; 10 mmol) was added. The reaction was allowed to stir at reflux for 5 h. After this time, the reaction was cooled to room temperature and then the butyl bromide (685 mg, 5 mmol) was added. The reaction mixture was allowed to stir at room temperature for additional 12 h. After this time, the mixture was diluted with ethyl acetate (20 mL) and washed with saturated aqueous NH 4 Cl (20 mL) and water (3×20 mL). The organic phase was separated, dried over MgSO 4 . Evaporation of solvent and purification of the residue by column chromatography (silica gel, petroleum ether) gave a colourless oil; yield: 1800 mg (83%); R f = 0.72 (petroleum ether). Butyl(hept-1-yn-1-yl)selenide (B)Using the procedure described above hept-1-yne (960 mg, 10 mmol) and 1bromobutane (685 mg, 5 mmol) gave a crude product that was purified by flash chromatography (silica gel, petroleum ether) to afford a colorless oil; yield: 1825 mg (79%); Rf = 0.77 (petroleum ether).Butyl(oct-1-yn-1-yl)selenide (C)Using the procedure described above hept-1-yne (960 mg, 10 mmol) and 1bromobutane (685 mg, 5 mmol) gave a crude product that was purified by flash chromatography (silica gel, petroleum ether) to a...

NbCl5-Mg Reagent System in Regio- and Stereoselective Synthesis of (2Z)-Alkenylamines and (3Z)-Alkenylols from Substituted 2-Alkynylamines and 3-Alkynylols

“…In order to further study transformations of acetylenic compounds under the organoniobium synthesis conditions, we made attempts to develop efficient reagents for transformations of niobiacyclopropene intermediates. Previously, we have demonstrated that sulfonic acid derivatives, such as sulfonyl halides, sulfonic acid silyl esters, alkylthiosulfonates, organic disulfides and diselenides are efficient electrophilic reagents for the functionalization of organoaluminum compounds, such as 1-alkenylalanes, which can be used to prepare the corresponding alkenyl halides [ 57 ], alkenylsilanes [ 58 ], alkenyl sulphides [ 59 , 60 ] and alkenyl selenides [ 61 ] in high yields under mild conditions. We expected that sulfonyl halides would also be reactive toward niobiacyclopropene intermediate generated in this reaction.…”

Recent Progress in Synthetic and Biological Application of Diorganyl Diselenides

“… [237] Following the hydrometallation of alkynes, a methylalumination of terminal and internal alkynes was reported to synthesize vinyl selenides 171 (Scheme 163). [238] The methylalumination leads to the initial formation of an alkenylalanes intermediate I , which reacts with diorganyl diselenides to give the product.…”

Stereoselective Synthesis of Z‐Vinyl Selenides Through the Reaction of Sodium Selenide with Organic Halides and Alkynes

“…Most general and efficient methods described for the preparation of vinyl selenides involves hydroselenation of alkynes, hydrometallation of alkynyl selenides, halogenation of alkynyl selenides, transition metal‐catalyzed diorganyl diselenides additions to alkynes, Horner, Wittig olefination, condensation reactions, selenium electrophilic addition to alkynes and selenium‐radical addition to alkynes . However, these very important methodologies require the use of metal transition, the previous preparation of diorganyl diselenides or very unstable selenols and the use of harsh reaction conditions, delivering serious limitations.…”