15962-89-7Relevant academic research and scientific papers
Trimethylsilyl chloride-accelerated reduction and pinacol coupling of carbonyl compounds by means of samarium diiodide
Honda, Toshio,Katoh, Miho
, p. 369 - 370 (1997)
The combination of samarium diiodide (SmI2) and trimethylsilyl chloride (Me3SiCl) in THF-HMPA is found to accelerate the reduction of sterically hindered and enolisable ketones, and also to accelerate pinacolisation of the carbonyl compounds depending on the reaction conditions.
Sodium Hypochlorite Pentahydrate as a Reagent for the Cleavage of trans-Cyclic Glycols
Kirihara, Masayuki,Osugi, Rie,Saito, Katsuya,Adachi, Kouta,Yamazaki, Kento,Matsushima, Ryoji,Kimura, Yoshikazu
, p. 8330 - 8336 (2019/06/24)
Sodium hypochlorite pentahydrate (NaOCl·5H2O) can be used toward the efficient glycol cleavage of trans-cyclic glycols, which are generally resistant to this transformation. Interestingly, the reaction of cis-cyclic glycols with NaOCl·5H2O is slower than that observed for the corresponding trans-isomer. This trans selectivity is in sharp contrast to traditional oxidants used for glycol cleavage. Acyclic glycols can also react efficiently with NaOCl·5H2O to form their corresponding carbonyl compounds in high yield.
Diastereoselective synthesis of trans-3,5-disubstituted dihydrofuran-2(3H)-ones via SmI2-mediated reductive coupling of 2-alkylacrylates of N,N-diisopropyl-2-hydroxybenzamide with aldehydes
Lai, Yecai,Sun, Lijie,Sit, Man Ki,Wang, Yan,Dai, Wei-Min
, p. 664 - 673 (2016/01/15)
Samarium(II) diiodide has been used to mediate reductive coupling reactions of aldehydes with a variety of substituted acrylates, in both achiral and chiral forms, for accessing substituted dihydrofuran-2(3H)-ones (γ-butyrolactones). Two major issues, concerning with self-dimerization of α-non-branched aliphatic aldehydes and low diastereoselectivity of the products, render limited application of the reductive coupling protocol in total synthesis of natural products. We report here on a novel type of substituted acrylates derived from the 2-amido arenols (HO-Aram) such as N,N-diisopropyl-2-hydroxybenzamide. The acrylates of HO-Aram enable: (a) preferential conjugate reduction of the acrylates than carbonyl reduction of aliphatic aldehydes, leading to diminished aldehyde self-dimerization; and (b) organization of an eight-membered ring among the amide carbonyl oxygen atom and samarium(III) to form a 7/8-bicyclic transition state, resulting in highly diastereoselective protonation of the samarium(III) enolate intermediate. Examples of synthesis of trans-3,5-disubstituted dihydrofuran-2(3H)-ones from 2-alkylacrylates of HO-Aram and aliphatic aldehydes are provided.
Synthesis of heterodinuclear hemisalen complexes on a hexaarylbenzene scaffold and their application for the cross-pinacol coupling reaction
Miyasaka, Akihiro,Amaya, Toru,Hirao, Toshikazu
, p. 1615 - 1621 (2014/03/21)
Intermolecular cross-pinacol coupling reaction between aliphatic and aromatic aldehydes by using heterodinuclear hemisalen complexes 1cis with vanadium(V) and titanium(IV) on a hexaarylbenzene scaffold is reported. Our ligand design is based on the individual activation of two aldehydes by vanadium and titanium, which are positioned with a suitable space on the rigid scaffold. Ligands such as 1cis were synthesized by Diels-Alder addition and decarbonylation reaction, followed by condensation of dialdehyde 3cis with various aminophenols. The influence of the substituents on the ligands on the pinacol coupling reaction was investigated. As a result, the reductive coupling reaction between aliphatic and aromatic aldehydes by using a catalytic amount of 1cis in the presence of Me3SiCl and Zn provided the corresponding cross-coupled 1,2-diol in good yields with high cross-selectivity. Working together: Dihemisalen ligands on a hexaaryl benzene scaffold were designed and the heterodinuclear complexes 1cis with vanadium(V) and titanium(IV) were synthesized from the corresponding disalicylaldehyde compound (see scheme). By using the heterodinuclear catalysts, the selective intermolecular cross-pinacol coupling reaction between aliphatic and aromatic aldehydes is demonstrated. Copyright
Ketyl-type radicals from cyclic and acyclic esters are stabilized by SmI2(H2O)n: the role of SmI2(H 2O)n in post-electron transfer steps
Szostak, Michal,Spain, Malcolm,Procter, David J.
supporting information, p. 8459 - 8466 (2014/06/24)
Mechanistic details pertaining to the SmI2-H2O- mediated reduction and reductive coupling of 6-membered lactones, the first class of simple unactivated carboxylic acid derivatives that had long been thought to lie outside the reducing range of SmI2, have been elucidated. Our results provide new experimental evidence that water enables the productive electron transfer from Sm(II) by stabilization of the radical anion intermediate rather than by solely promoting the first electron transfer as originally proposed. Notably, these studies suggest that all reactions involving the generation of ketyl-type radicals with SmI2 occur under a unified mechanism based on the thermodynamic control of the second electron transfer step, thus providing a blueprint for the development of a broad range of novel chemoselective transformations via open-shell electron pathways.
Catalytic enantioselective alkylation and arylation of aldehydes by using grignard reagents
Muramatsu, Yusuke,Kanehira, Shinichi,Tanigawa, Masato,Miyawaki, Yuta,Harada, Toshiro
experimental part, p. 19 - 32 (2010/03/25)
We have developed an efficient and practical method for the catalytic enantioselective alkylation and arylation of aldehydes by using Grignard reagents in combination with titanium tetraisopropoxide. Grignard reagents and titanium tetraisopropoxide are mixed in a molar ratio of ca. 1:2. In the presence of catalyst (24mol%), which is formed in situ from a BINOL ligand 4a and 4b and titanium tetraisopropoxide, the resulting mixed titanium reagents undergo addition to aldehydes with high enantioselectivities (typically >90% ee) and high yields. The method is applicable to various combination of aldehydes (R1CHO; R1 = aryl, heteroaryl, 1-alkenyl, and alkyl) and Grignard reagents (R2MgX; R2 = primary alkyl and aryl). Thus, a variety of enantiomerically enriched secondary alcohols (R1CH*(OH)R2) can be prepared. It has also been demonstrated that functionalized aryl Grignard reagents can be employed to generate highly functionalized diarylmethanols. The preparative utility of the method has been shown by the fact that the reaction is operationally simple, can be carried out on a 10-mmol scale without any difficulty, and the ligands can be readily recovered.
Reductive self-coupling reaction of imines and aldehydes induced by strontium metal
Miyoshi, Norikazu,Kohno, Tadashi,Wada, Makoto,Matsunaga, Sei,Mizota, Isao,Shimizu, Makoto
experimental part, p. 984 - 985 (2012/10/18)
Aromatic aldimines reacted with Sr in the presence of a catalytic amount of iodine to give self-coupling products in good yields, whereas aromatic and aliphatic aldehydes underwent a similar reaction effected by the combined use of Sr and Al(OEt)3. Copyright
Catalytic asymmetric alkylation of aldehydes with Grignard reagents
Muramatsu, Yusuke,Harada, Toshiro
, p. 1088 - 1090 (2008/09/21)
(Chemical Equation Presented) Added benefits: Grignard reagents can be employed in the asymmetric alkylation of aldehydes by using a titanium(IV) catalyst derived from binol in the presence of excess titanium tetraisopropoxide (see scheme). The reaction proceeds with a low catalyst loading (2 mol%) and exhibits high enantioselectivity for both aromatic and unsaturated aldehydes and for both alkyl and aryl Grignard reagents.
Samarium diiodide-catalyzed diastereoselective pinacol couplings
Aspinall, Helen C.,Greeves, Nicholas,Valla, Carine
, p. 1919 - 1922 (2007/10/03)
(Chemical Equation Presented) A complex of samarium diiodide (Sml 2) with tetraglyme catalyzes the intermolecular pinacol coupling of aromatic or aliphatic aldehydes at loadings of 10 mol % in the presence of Me2SiCl2 and Mg. Diastereoselectivity of up to 95/5 (±/meso) has been achieved for aliphatic aldehydes and up to 19/81 (±/meso) for aromatic aldehydes. De values of up to 99% have been achieved in intramolecular pinacol coupling reactions using the Sml 2/tetraglyme/Mg/Me2SiCl2 catalytic system.
Preferential catalytic hydrogenation of aromatic compounds versus ketones with a palladium substituted polyoxometalate as pre-catalyst
Kogan, Vladimir,Aizenshtat, Zeev,Neumann, Ronny
, p. 272 - 274 (2007/10/03)
A palladium-substituted polyoxometalate having a Keggin structure, supported on γ-alumina or active carbon, was used as a catalyst precursor for catalytic hydrogenation. The catalyst system enabled fast hydrogenation of arenes at 30 bar H2 and 230°C. Most interesting was the finding that arenes could be selectively reduced in the presence of distal ketone groups under similar conditions, 30 bar H2 and 200°C. For example, 1-phenyl-2-propanone yielded 1-cyclohexyl-2-propanone with no reduction of the ketone moiety. Additionally, aromatic compounds with vicinal (conjugated) ketone moieties underwent complete hydrogenation to saturated hydrocarbons and catalytic McMurry coupling was observed for aliphatic aldehydes.
