The Cp 2 ZrCl 2-catalyzed methylalumination of 1-alkynyl sulfones and 1-alkynyl sulfides with Me 3 Al, followed by deuterolysis or hydrolysis, affords the corresponding β,β-disubstituted 1-alkenyl sulfones and 1-alkenyl sulfides in high yields. S-Methyl methanethiosulfonate is shown to be a convenient and efficient sulfanylating agent for 1-alkenylaluminum derivatives.
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...
The reaction of 1-alkynyl sulfides and alkynyl sulfoxides with Et3Al under zirconocene catalysis conditions has been studied. The interaction between 1-alkynyl sulfides and Et3Al in the presence of catalytic amounts of Cp2ZrCl2 leads to trisubstituted 1-alkenyl sulfides in moderate to good yields (56–73%) with high regioselectivity and stereoselectivity. 1-Alkynyl sulfoxides, upon treatment with Et3Al under the same reaction conditions, undergoes reduction to give sulfides. The excess of Et3Al (7 equiv) in this reaction causes cyclic carboalumination of in situ generated 1-alkynyl sulfide to form trisubstituted 1-alkenyl sulfides in quantitative yield.
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