1565-86-2Relevant academic research and scientific papers
Chiral secondary alcohol-induced asymmetric autocatalysis: correlation between the absolute configuration of the chiral initiators and the product
Shibata, Takanori,Iwahashi, Kimiko,Kawasaki, Tsuneomi,Soai, Kenso
, p. 1759 - 1762 (2007)
In the presence of various chiral secondary alcohols as chiral initiators, an enantioselective alkylation of a pyrimidine-5-carbaldehyde using diisopropylzinc was examined: a pyrimidyl alkanol was obtained in high yield and enantiomeric excess. The correl
Catalytic activation of trichlorosilane for efficient and stereoselective reduction of ketones
Iwasaki, Fumiaki,Onomura, Osamu,Mishima, Katsuhiko,Maki, Toshihide,Matsumura, Yoshihiro
, p. 7507 - 7511 (1999)
Some kinds of N-formyl cyclic amine derivatives were found to be effective activators for trichlorosilane to reduce ketones. Namely, a catalytic amount of these activators were sufficient to complete the reduction of ketones with trichlorosilane, and the reduction of ketones by trichlorosilane with optically active activators gave enantiomerically enriched sec-alcohols in some extent of optical yields (up to 51% ee).
The generation of palladium silicide nanoalloy particles in a SiCN matrix and their catalytic applications
Zaheer, Muhammad,Motz, Guenter,Kempe, Rhett
, p. 18825 - 18831 (2011)
The synthesis, characterization and catalytic studies of single phase palladium silicide nanoalloy particles supported by a polymer derived, non-oxide SiCN matrix (Pd2Si@SiCN) are reported. Simultaneous chemical modification of a polyorganosilazane as well as its cross-linking was achieved by the use of an aminopyridinato palladium complex at room temperature. Cross-linking takes place with an evolution of hydrogen and increases the ceramic yield by the retention of carbon and nitrogen atoms. Liberation of ligand, as confirmed by 1H NMR spectroscopy, provides indirect evidence of the transfer of palladium to the nitrogen functions producing metal modified polyorganosilazane whose pyrolysis at 1100 °C under nitrogen atmosphere provides Pd2Si@SiCN. Powder X-ray diffraction (PXRD) studies confirmed the presence of the hexagonal Pd2Si phase in the amorphous SiCN matrix. The size of the particles formed seems to depend upon the nature of the solvent used in the cross-linking step. The amount of palladium complex added seems not to affect the size of particles formed but does increase their population density. Pd2Si@SiCN catalysts were found active for the hydrogenation of ketones. The selectivity of the reaction towards the alcoholic product remains very high. The conversion of the reaction however decreases both with increase in alkyl chain length as well as its branching at alpha carbon. The recyclable Pd2Si@SiCN could be a suitable choice for catalytic transformations under a harsh chemical environment and at higher temperatures.
Synthesis of β-nitro ketones from geminal bromonitroalkanes and silyl enol ethers by visible light photoredox catalysis
Cao, Haoying,Ma, Shanshan,Feng, Yanhong,Guo, Yawen,Jiao, Peng
, p. 1780 - 1783 (2022/02/17)
Various β-nitro ketones, including those bearing a β-tertiary carbon, were prepared from geminal bromonitroalkanes and trimethylsilyl enol ethers of a broad range of ketones by visible light photoredox catalysis, which were then easily converted into β-amino ketones, 1,3-amino alcohols, α,β-unsaturated ketones, β-cyano ketones and γ-nitro ketones.
Copper-Catalyzed Enantioconvergent Cross-Coupling of Racemic Alkyl Bromides with Azole C(sp2)?H Bonds
Chang, Xiao-Yong,Chen, Ji-Jun,Gu, Qiang-Shuai,Jiang, Sheng-Peng,Li, Zhong-Liang,Liu, Lin,Liu, Xiao-Dong,Liu, Xin-Yuan,Su, Xiao-Long,Wang, Fu-Li,Yang, Chang-Jiang,Ye, Liu
supporting information, p. 380 - 384 (2020/10/30)
The development of enantioconvergent cross-coupling of racemic alkyl halides directly with heteroarene C(sp2)?H bonds has been impeded by the use of a base at elevated temperature that leads to racemization. We herein report a copper(I)/cinchona-alkaloid-derived N,N,P-ligand catalytic system that enables oxidative addition with racemic alkyl bromides under mild conditions. Thus, coupling with azole C(sp2)?H bonds has been achieved in high enantioselectivity, affording a number of potentially useful α-chiral alkylated azoles, such as 1,3,4-oxadiazoles, oxazoles, and benzo[d]oxazoles as well as 1,3,4-triazoles, for drug discovery. Mechanistic experiments indicated facile deprotonation of an azole C(sp2)?H bond and the involvement of alkyl radical species under the reaction conditions.
Enzymatic Primary Amination of Benzylic and Allylic C(sp3)-H Bonds
Jia, Zhi-Jun,Gao, Shilong,Arnold, Frances H.
supporting information, p. 10279 - 10283 (2020/07/27)
Aliphatic primary amines are prevalent in natural products, pharmaceuticals, and functional materials. While a plethora of processes are reported for their synthesis, methods that directly install a free amine group into C(sp3)-H bonds remain unprecedented. Here, we report a set of new-to-nature enzymes that catalyze the direct primary amination of C(sp3)-H bonds with excellent chemo-, regio-, and enantioselectivity, using a readily available hydroxylamine derivative as the nitrogen source. Directed evolution of genetically encoded cytochrome P411 enzymes (P450s whose Cys axial ligand to the heme iron has been replaced with Ser) generated variants that selectively functionalize benzylic and allylic C-H bonds, affording a broad scope of enantioenriched primary amines. This biocatalytic process is efficient and selective (up to 3930 TTN and 96percent ee), and can be performed on preparative scale.
Organomagnesium Based Flash Chemistry: Continuous Flow Generation and Utilization of Halomethylmagnesium Intermediates
Von Keutz, Timo,Cantillo, David,Kappe, C. Oliver
supporting information, p. 7537 - 7541 (2020/10/12)
The generation of highly unstable chloromethylmagnesium chloride in a continuous flow reactor and its reaction with aldehydes and ketones is reported. With this strategy, chlorohydrins and epoxides were synthesized within a total residence time of only 2.6 s. The outcome of the reaction can be tuned by simply using either a basic or an acidic quench. Very good to excellent isolated yields, up to 97%, have been obtained for most cases (30 examples).
Phosphine-NHC Manganese Hydrogenation Catalyst Exhibiting a Non-Classical Metal-Ligand Cooperative H2 Activation Mode
Buhaibeh, Ruqaya,Filippov, Oleg A.,Bruneau-Voisine, Antoine,Willot, Jérémy,Duhayon, Carine,Valyaev, Dmitry A.,Lugan, No?l,Canac, Yves,Sortais, Jean-Baptiste
supporting information, p. 6727 - 6731 (2019/04/17)
Deprotonation of the MnI NHC-phosphine complex fac-[MnBr(CO)3(κ2P,C-Ph2PCH2NHC)] (2) under a H2 atmosphere readily gives the hydride fac-[MnH(CO)3(κ2P,C-Ph2PCH2NHC)] (3) via the intermediacy of the highly reactive 18-e NHC-phosphinomethanide complex fac-[Mn(CO)3(κ3P,C,C-Ph2PCHNHC)] (6 a). DFT calculations revealed that the preferred reaction mechanism involves the unsaturated 16-e mangana-substituted phosphonium ylide complex fac-[Mn(CO)3(κ2P,C-Ph2P=CHNHC)] (6 b) as key intermediate able to activate H2 via a non-classical mode of metal-ligand cooperation implying a formal λ5-P–λ3-P phosphorus valence change. Complex 2 is shown to be one of the most efficient pre-catalysts for ketone hydrogenation in the MnI series reported to date (TON up to 6200).
Novel Chiral PNNP Ligands with a Pyrrolidine Backbone – Application in the Fe-Catalyzed Asymmetric Transfer Hydrogenation of Ketones
Mercadé, Elisabet,Zangrando, Ennio,Clotet, Anna,Claver, Carmen,Godard, Cyril
, p. 4211 - 4220 (2019/11/05)
The PNNP ligand (R,R)-{PPh2(2-C6H4)CH=N(pyrrolidine-NBn)-}2 2 was prepared by condensation between 2-diphenylphosphino benzaldehyde and the pyrrolidine-substituted diamine 1. Reduction with NaBH4 in MeOH afforded (R,R)-{PPh2(2-C6H4)CH–NH(pyrrolidine-NBn)-}2 3. The corresponding iron(II) complexes [FeCl2(2)] (4), [Fe(CH3CN)2(2)](BF4)2 (5) and [Fe(CH3CN)2(2)](PF6)2 (6) were synthesized and fully characterized by NMR, ESI-HRMS, and EA. DFT calculations for complexes [FeCl2(2)] (4) and [Fe(CH3CN)2(2)](BF4)2 (5) were carried out in order to investigate the stability of related structures. The PNNP ligands 2 and 3 in combination with Fe3(CO)12 as iron source were tested as catalysts in the asymmetric transfer hydrogenation of a variety of ketones with conversions higher than 95 % and enantioselectivities up to 97 %.
Copper(I)-Catalyzed Enantioconvergent Borylation of Racemic Benzyl Chlorides Enabled by Quadrant-by-Quadrant Structure Modification of Chiral Bisphosphine Ligands
Iwamoto, Hiroaki,Endo, Kohei,Ozawa, Yu,Watanabe, Yuta,Kubota, Koji,Imamoto, Tsuneo,Ito, Hajime
supporting information, p. 11112 - 11117 (2019/07/17)
The first copper(I)-catalyzed enantioselective borylation of racemic benzyl chlorides has been realized by a quadrant-by-quadrant structure modulation of QuinoxP*-type bisphosphine ligands. This reaction converts racemic mixtures of secondary benzyl chlorides into the corresponding chiral benzylboronates with high enantioselectivity (up to 92 % ee). The results of mechanistic studies suggest the formation of a benzylic radical intermediate. The results of DFT calculations indicate that the optimal bisphosphine-copper(I) catalyst engages in noncovalent interactions that efficiently recognize the radical intermediate, and leads to high levels of enantioselectivity.
