1123-85-9Relevant academic research and scientific papers
Anti-Markovnikov alkene oxidation by metal-oxo–mediated enzyme catalysis
Hammer, Stephan C.,Kubik, Grzegorz,Watkins, Ella,Huang, Shan,Minges, Hannah,Arnold, Frances H.
, p. 215 - 218 (2017)
Catalytic anti-Markovnikov oxidation of alkene feedstocks could simplify synthetic routes to many important molecules and solve a long-standing challenge in chemistry. Here we report the engineering of a cytochrome P450 enzyme by directed evolution to catalyze metal-oxo–mediated anti-Markovnikov oxidation of styrenes with high efficiency. The enzyme uses dioxygen as the terminal oxidant and achieves selectivity for anti-Markovnikov oxidation over the kinetically favored alkene epoxidation by trapping high-energy intermediates and catalyzing an oxo transfer, including an enantioselective 1,2-hydride migration. The anti-Markovnikov oxygenase can be combined with other catalysts in synthetic metabolic pathways to access a variety of challenging anti-Markovnikov functionalization reactions.
Improved Catalytic Activity and Stability of a Palladium Pincer Complex by Incorporation into a Metal-Organic Framework
Burgess, Samantha A.,Kassie, Abebu,Baranowski, Sarah A.,Fritzsching, Keith J.,Schmidt-Rohr, Klaus,Brown, Craig M.,Wade, Casey R.
, p. 1780 - 1783 (2016)
A porous metal-organic framework Zr6O4(OH)4(L-PdX)3 (1-X) has been constructed from Pd diphosphinite pincer complexes ([L-PdX]4- = [(2,6-(OPAr2)2C6H3)PdX]4-, Ar = p-C6H4CO2-, X = Cl, I). Reaction of 1-X with PhI(O2CCF3)2 facilitates I-/CF3CO2- ligand exchange to generate 1-TFA and I2 as a soluble byproduct. 1-TFA is an active and recyclable catalyst for transfer hydrogenation of benzaldehydes using formic acid as a hydrogen source. In contrast, the homogeneous analogue tBu(L-PdTFA) is an ineffective catalyst owing to decomposition under the catalytic conditions, highlighting the beneficial effects of immobilization.
On the intermolecular interaction of N-benzylquininium chloride or quinine with some carbonyl group containing compounds
Avila, Thais C.,Reginato, Marcelo M.,Di Vitta, Cláudio,Ducati, Lucas C.,Andrade, Leandro H.,Marzorati, Liliana
, p. 2152 - 2157 (2016)
Interactions between N-benzylquininium chloride (Quibec) and some carbonyl group containing compounds were investigated using 1H NMR and theoretical calculations. Results highlight the importance of the hydrogen bonding between the Quibec C-9 h
Catalyst Repurposing Sequential Catalysis by Harnessing Regenerated Prolinamide Organocatalysts as Transfer Hydrogenation Ligands
Bourgeois, Frederic,Medlock, Jonathan A.,Bonrath, Werner,Sparr, Christof
, p. 110 - 115 (2020)
A catalyst repurposing strategy based on a sequential aldol addition and transfer hydrogenation giving access to enantiomerically enriched α-hydroxy-γ-butyrolactones is described. The combination of a stereoselective, organocatalytic step, followed by an efficient catalytic aldehyde reduction induces an ensuing lactonization to provide enantioenriched butyrolactones from readily available starting materials. By capitalizing from the capacity of prolineamides to act as both an organocatalyst and a transfer hydrogenation ligand, catalyst repurposing allowed the development of an operationally simple, economic, and efficient sequential catalysis approach.
Copper-catalyzed enantioselective hydroboration of unactivated 1, 1-disubstituted alkenes
Jang, Won Jun,Song, Seung Min,Moon, Jong Hun,Lee, Jin Yong,Yun, Jaesook
, p. 13660 - 13663 (2017)
We report an efficient and highly enantioselective hydroboration of aliphatic 1, 1-disubstituted alkenes with pinacolborane using a phosphine-Cu catalyst. The method allows facile preparation of enantiomerically enriched β-chiral alkyl pinacolboronates from a range of 1, 1-disubstituted alkenes with high enantioselectivity up to 99% ee. Unprecedented enantiodiscrimination between the geminal alkyl substituents was observed with functional group compatibility in the hydroboration. Furthermore, a catalyst loading as low as 1 mol % furnished the desired product without a decrease in yield or selectivity, demonstrating its efficiency in gram scale synthesis.
Enantioselective Ir-catalyzed hydrogenation of minimally functionalized olefins using pyranoside phosphinite-oxazoline ligands
Mazuela, Javier,Pamies, Oscar,Dieguez, Montserrat
, p. 2139 - 2145 (2013)
Pyranoside phosphinite-oxazoline ligands prepared from readily available (+)-D-glucosamine were applied to the Ir-catalyzed asymmetric hydrogenation of minimally functionalized olefins. Our results show that the enantioselectivity is dependent on the ozaxoline and the phosphinite moieties and the substrate structure. By carefully selecting the ligand components, enantioselectivities up to 99 % were obtained in the asymmetric reduction of several (E)- and (Z)-trisubstituted and 1,1-disubstituted olefins. The asymmetric hydrogenation was also performed using propylene carbonate as solvent, which allowed the iridium catalysts to be reused and maintained the high enantioselectivities. Copyright
Vanadium hydrogen sulfate (I): Chemoselective trimethylsilylation of alcohols and deprotection of trimethylsilyl ethers
Shirini, Farhad,Zolfigol, Mohammad Ali,Abedini, Masoumeh,Sakhaei, Ali Reza
, p. 943 - 946 (2008)
Trimethylsilylation of alcohols with hexamethyldisilazane (HMDS) catalyzed by V(HSO4)3 under mild and completely heterogeneous reaction condition is reported. The method is highly chemoselective for the protection of alcohols in the presence of phenols, amines and thiols. Also, the deprotection of trimethylsilyl ethers is performed in the presence of V(HSO 4)3 at room temperature in good to high yields.
Regioselective methylation of the secondary carbinol center of prim, sec-diols
Yoshida, Hifumi,Takada, Akinori,Mitsunobu, Oyo
, p. 3007 - 3010 (1998)
Reaction of 2-oxo-4-phenyl-1,3,2-dioxathiolane and 2-oxo-4-(tert- butyldiphenylsilylmethyl)-13,2-dioxathiolane with trimethylaluminium selectively took place at the secondary carbinol center to give 2-phenyl-1- propanol and 3-(tert-butyldiphenylsilyl)-2-methylpropanol. When the endo- or exo-isomer of (S)-2-oxo-4-phenyl-13,2-dioxathiolane reacted with trimethylaluminium, (R)-2-phenyl-1-propanol was obtained in 75% ee or 90% ee, respectively.
Electronic effects in asymmetric hydroboration
Garner, Charles M.,Chiang, Shirley,Nething, Matthew,Monestel, Robert
, p. 8339 - 8342 (2002)
To determine whether electronic effects are operative in asymmetric hydroboration, a series of para-substituted 2-aryl-1-propenes were prepared and reacted with four asymmetric borane reagents. A significant correlation between the electronic nature of the para-substituent and the degree of asymmetric induction was observed only for a chloroborane-ether complex, not for any of several simple alkylboranes. A quantitative analysis of the relative reactivities is also given.
Four-Coordinated Manganese(II) Disilyl Complexes for the Hydrosilylation of Aldehydes and Ketones with 1,1,3,3-Tetramethyldisiloxane
Saito, Kyoka,Ito, Tatsuyoshi,Arata, Shogo,Sunada, Yusuke
, p. 1152 - 1156 (2021)
The coordinatively unsaturated manganase(II) bis(supersilyl) complex Mn[Si(SiMe3)3]2(THF)2 (2) was synthesized in one step via the reaction of MnBr2 with two equivalents of KSi(SiMe3)3 in THF. Complex 2 acts as an effective precatalyst for the catalytic hydrosilylation of aldehydes and ketones with 1,1,3,3-tetramethyldisiloxane (TMDS). The catalytic efficiency can be improved by combining 2 and adamantyl isocyanide (CNAd). The stoichiometric reaction of 2 and two equivalents of CNAd led to the isolation of Mn[Si(SiMe3)3]2(CNAd)2 (3) in high yield. Complex 3 shows superior catalytic performance than 2 in the hydrosilylation of relatively unreactive ketones.
