32780-80-6Relevant academic research and scientific papers
Regio- And Stereoselective Hydroiodination of Internal Alkynes with Ex Situ-Generated HI
Nozawa-Kumada, Kanako,Noguchi, Koto,Akada, Tomoya,Shigeno, Masanori,Kondo, Yoshinori
supporting information, p. 6659 - 6663 (2021/09/08)
Herein, we report an efficient and practical hydroiodination of internal alkynes using HI generated ex situ from the readily available triethylsilane and I2. This system offers high regio- and stereoselectivity to afford (E)-vinyl iodides in good yields under mild conditions. Furthermore, the hydroiodination reaction shows high functional group tolerance toward alkyl, methoxy, halogen, trifluoromethyl, cyano, ester, halomethyl, acid-sensitive silyl ether, and acetal moieties.
Metal-Free Transfer Hydroiodination of C-C Multiple Bonds
Chen, Weiqiang,Walker, Johannes C. L.,Oestreich, Martin
supporting information, p. 1135 - 1140 (2019/01/11)
The design and a gram-scale synthesis of a bench-stable cyclohexa-1,4-diene-based surrogate of gaseous hydrogen iodide are described. By initiation with a moderately strong Br?nsted acid, hydrogen iodide is transferred from the surrogate onto C-C multiple bonds such as alkynes and allenes without the involvement of free hydrogen iodide. The surrogate fragments into toluene and ethylene, easy-to-remove volatile waste. This hydroiodination reaction avoids precarious handling of hydrogen iodide or hydroiodic acid. By this, a broad range of previously unknown or difficult-to-prepare vinyl iodides can be accessed in stereocontrolled fashion.
Activation of vinyl iodides for the highly enantioselective addition to aldehydes
DeBerardinis, Albert M.,Turlington, Mark,Pu, Lin
supporting information; experimental part, p. 2368 - 2370 (2011/04/21)
(Chemical Equation Presented) Mild and tolerant: Vinylzinc reagents were directly prepared from the reaction of vinyl iodides with ZnEt2 under mild reaction conditions. The compound (S)-1 was found to catalyze the addition of the vinylzinc reag
Titanium tetraiodide-promoted tandem prins reaction of alkynes with acetals: Synthesis of (Z,Z)-1,5-Diiodo-1,3,5-triarylpenta-1,4-dienes
Shimizu, Makoto,Okura, Kanako,Arai, Takuya,Hachiya, Iwao
scheme or table, p. 1052 - 1054 (2011/01/10)
In the presence of titanium tetraiodide, a tandem Prins reaction of alkynes proceeded with acetals to give (Z,Z)-1,5diiodo-1,3,5-triarylpenta-1,4-dienes in good yields, where an intriguing reversal of the stereoselectivity was observed among titanium tetr
Surface-Mediated Reactions. 4. Hydrohalogenation of Alkynes
Kropp, Paul J.,Crawford, Scott D.
, p. 3102 - 3112 (2007/10/02)
The use of appropriately prepared silica gel and alumina has been found to mediate the addition of hydrogen halides to alkynes.The technique has been rendered even more convenient by the use of various organic and inorganic acid halides that react in the presence of silica gel or alumina to generate hydrogen halides in situ.Treatment in this fashion of 1-propynylbenzene (1), which underwent no reaction in CH2Cl2 solution saturated with HCl, readily afforded the syn addition product, alkenyl chloride (E)-4a.On extended treatment (E)-4a underwent subsequent iaomerization to the thermodynamically more stable Z isomer.Thus either isomer of 4a could be obtained in good yield depending on the reaction conditions.In a similar way bromides (E)- and (Z)-4b were obtained without competing formation of the radical products (E)- and (Z)-5, which occurred in solution.In contrast with solution-phase hydroiodination of alkyne 1, which slowly afforded iodide (E)-4c, surface-mediated addition readily afforded (E)-4c, followed by isomerization to the Z isomer.E ->/- Z equilibration of the alkenyl halides 4 was shown to involve, at last in part, addition-elimination via the gem-dihalides 13.Analogous behavior was exhibited by the phenylalkynes 2 and 3 on surface-mediated hydrohalogenation.Surface-mediated addition of HBr and HI to the internal alkylalkyne 14 afforded principally the anti addition products (Z)-15b,c.Treatment of the terminal alkynes 17 and 22 with (COBr)2 over alumina gave the dibromides 20 and 24/25, respectively, whereas use of acetyl bromide as the HBr precursor afforded the alkenyl bromides 18b and 23.
Mechanism, regiochemistry, and stereochemistry of the insertion reaction of alkynes with methyl(2,4-pentanedionato)(triphenylphosphine)nickel. A cis insertion that leads to trans kinetic products
Huggins, John M.,Bergman, Robert G.
, p. 3002 - 3011 (2007/10/02)
This study reports the rapid reaction under mild conditions of internal and terminal alkynes with methyl(2,4-pentanedionato)(triphenylphosphine)nickel (1) in aromatic and ethereal solvents. In all cases vinylnickel products (2) are formed by insertion of the alkyne into the nickel-methyl bond. The regiochemistry is unusual; unsymmetrical alkynes give selectively the one regioisomer with the sterically largest substituent next to the nickel atom. So that the stereochemistry of the initial insertion could be investigated, an X-ray diffraction study of the reaction of 1 and diphenylacetylene was carried out. This showed that the vinylnickel complex formed by overall trans insertion was the product of the reaction. Furthermore, subsequent slow isomerization of this complex, to a mixture of it and the corresponding cis isomer, demonstrated that this trans addition product is the kinetic product of the reaction. In studies with other alkynes, the product of trans addition was not always exclusively (or even predominantly) formed, but the ratio of the stereoisomers formed kinetically was substantially different from the thermodynamic ratio. Isotope labeling, added phosphine, and other experiments have allowed us to conclude that the mechanism of this reaction does involve cis addition. However, a coordinatively unsaturated vinylnickel intermediate is initially formed, which can undergo rapid, phosphine-catalyzed cis-trans isomerization in competition with its conversion to the isolable phosphine-substituted products.
