96304-40-4Relevant academic research and scientific papers
1,5,7-Triazabicyclo[4.4.0]dec-5-ene Enhances Activity of Peroxide Intermediates in Phosphine-Free α-Hydroxylation of Ketones
Wang, Yongtao,Lu, Rui,Yao, Jia,Li, Haoran
supporting information, p. 6631 - 6638 (2021/02/05)
The critical role of double hydrogen bonds was addressed for the aerobic α-hydroxylation of ketones catalyzed by 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD), in the absence of either a metal catalyst or phosphine reductant. Experimental and theoretical investigations were performed to study the mechanism. In addition to initiating the reaction by proton abstraction, a more important role of TBD was revealed, that is, to enhance the oxidizing ability of peroxide intermediates, allowing DMSO to be used rather than commonly used phosphine reductants. Further characterizations with nuclear Overhauser effect spectroscopy (NOESY) confirmed the presence of double hydrogen bonds between TBD and the ketone, and kinetic studies suggested the attack of dioxygen on the TBD-enol adduct to be the rate-determining step. This work should encourage the application of TBD as a catalyst for oxidations.
Oxidation of Vicinal Diols to α-Hydroxy Ketones with H2O2 and a Simple Manganese Catalyst
Mecozzi, Francesco,Dong, Jia Jia,Saisaha, Pattama,Browne, Wesley R.
supporting information, p. 6919 - 6925 (2017/12/26)
α-Hydroxy ketones are valuable synthons in organic chemistry. Here we show that oxidation of vic-diols to α-hydroxy ketones with H2O2 can be achieved with an in situ prepared catalyst based on manganese salts and pyridine-2-carboxylic acid. Furthermore the same catalyst is effective in alkene epoxidation, and it is shown that alkene oxidation with the MnII catalyst and H2O2 followed by Lewis acid ring opening of the epoxide and subsequent oxidation of the alkene to α-hydroxy ketones can be achieved under mild (ambient) conditions.
Improved methods for thermal rearrangement of alicyclic α-hydroxyimines to α-aminoketones: Synthesis of ketamine analogues as antisepsis candidates
Elhawi, Hagit,Eini, Hadar,Douvdevani, Amos,Byk, Gerardo
, p. 6784 - 6807 (2012/09/07)
Ketamine is an analgesic/anesthetic drug, which, in combination with other drugs, has been used as anesthetic for over 40 years. Ketamine induces its analgesic activities by blocking the N-methyl-D-aspartate (NMDA) receptor in the central nervous system (CNS). We have reported that low doses of ketamine administrated to patients before incision significantly reduced post-operative inflammation as reflected by reduced interleukin-6 (IL-6) sera-levels. Our data demonstrated in a rat model of Gram-negative bacterial-sepsis that if we inject a low dose of ketamine following bacterial inoculation we reduce mortality from approximately 75% to 25%. Similar to what we have observed in operated patients, the levels of TNF-α and IL-6 in ketamine-treated rats were significantly lower than in septic animals not treated with ketamine. On the base of these results, we have designed and synthesized series of new analogues of ketamine applying a thermal rearrangement of alicyclic α-hydroxyimines to α-aminoketones in parallel arrays. One of the analogues (compound 6e) displayed high activity in down-regulating the levels of IL-6 and TNF-α in vivo as compared to ketamine.
Catalytic enantioselective crossed aldehyde-ketone benzoin cyclization
Takikawa, Hiroshi,Hachisu, Yoshifumi,Bode, Jeffrey W.,Suzuki, Keisuke
, p. 3492 - 3494 (2007/10/03)
(Chemical Equation Presented) Joining together: The catalytic, asymmetric benzoin cyclization of a wide variety ketoaldehydes using chiral triazolium salts of type 1 has been carried out (see scheme). The corresponding cyclized products were prepared in h
Thiazol-2-ylidene catalysis in intramolecular crossed aldehyde-ketone benzoin reactions
Enders, Dieter,Niemeier, Oliver
, p. 2111 - 2114 (2007/10/03)
Intramolecular crossed aldehyde-ketone benzoin-type reactions catalyzed by nucleophilic carbenes, easily generated from commercially available thiazolium salts as precatalysts, are described. Five- and six-membered cyclic acyloins are obtained in moderate to good yields. Depending on the structure of the aldehyde-ketone substrate, an interchange of the alcohol and ketone function of the resulting acyloin is possible. Simple aldehyde-ketones are not good substrates due to the competing intermolecular reaction. Starting from biphenyl-2,2′-dicarbaldehyde, the intermediate acyloin is converted to 9,10-phenanthrenequinone by mild air oxidation.
Direct conversion of tert-β-bromo alcohols to ketones with zinc sulfide and DMSO
Bettadaiah,Gurudutt,Srinivas
, p. 2460 - 2462 (2007/10/03)
tert-β-Bromo alcohols, derived from simple monoterpene hydrocarbons, react with zinc sulfide in dimethyl sulfoxide to afford saturated ketones as the major and hydroxy ketones as the minor products. The reaction involves initial nucleophilic attack by DMSO on the carbon attached to the halogen, which is assisted by electrophilic zinc sulfide. Subsequent Kornblum type oxidation yields the α-hydroxy ketone. On the other hand, abstraction of proton β to the hydroxyl group followed by an attack of the neighboring hydroxyl moiety on the sulfur of the dimethylsulfoxonium intermediate and its subsequent collapse yields an enol, which tautomerizes to a saturated ketone. The latter pathway is predominantly followed.
Asymmetric catalysis. Part 153: Metal-catalysed enantioselective α-ketol rearrangement
Brunner, Henri,Kagan, Henri B.,Kreutzer, Georg
, p. 2177 - 2187 (2007/10/03)
Promoted by catalytic amounts of Ni complexes tertiary α-hydroxyketones 1a, 3a-5a undergo rearrangement, forming chiral isomers 1b, 3b-5b. The best enantioselection was obtained with the model system 1-benzoylcyclopentanol 4a/2-hydroxy-2-phenylcyclohexanone 4b. In a ligand screening 2-[4-(S)-tert-butyloxazolin-2-yl]pyridine gave the highest enantiomeric excess of 46% (S)-4b. The analogous isomerisation reactions of α-hydroxyimines 6a, 7a forming chiral α-aminoketones 6b, 7b were established.
Directive effect of the 2- and 3-axial hydroxy groups that appeared in the complex metal hydride reduction of cyclohexanones
Senda,Kikuchi,Inui,Itoh
, p. 237 - 242 (2007/10/03)
A directive effect of the 2-axial hydroxy group appeared in the LiAlH4, NaBH4, and Zn(BH4)2 reduction of cyclohexanone, while the 3-axial hydroxy group exhibited a steric hindrance. The distance between the carbonyl carbon and the hydroxy group interacting with the hydride reagent was responsible for such a difference. In the reduction of Na[B(OAc)3H], the 2- and 3-axial hydroxycyclohexanones gave the products obtained by the hydride approaching from the side of the hydroxy group. The key point of the stereoselectivity was the formation of Na[B(OAc)2(OR)H, which was more reactive than the parent hydride, by exchanging the acetate ion with the alkoxide. Although the reduction was performed under the condition that the hydride/substrate ratio was 1, the conversion of the hydroxy ketone to an alcohol were 4, NaBH4, and Zn(BH4)2 reductions in tetrahydrofuran. The conversions in the NaBH4 reduction in ethanol were > 90%.
The Cp2TiPh-mediated reductive radical cyclization of cyanoketones and related reactions. Efficient trapping of ketyl radicals by Cp2TiPh- coordinated polar multiple bonds
Yamamoto, Yoshihiko,Matsumi, Daisuke,Hattori, Reiko,Itoh, Kenji
, p. 3224 - 3229 (2007/10/03)
The reductive radical cyclization of cyanoketones was achieved using Cp2TiPh. The Ti(III) reagent was prepared by the sequential addition of i- PrMgCl and PhMgBr to commercial Cp2TiCl2 in this order and used effectively without isolation. The cyclization of the γ- and δ-cyanoketones was performed in toluene at ambient temperature for several hours to give α- hydroxycyclopentanones and hexanones in moderate to good yields, respectively. The titanium reagent independently coordinates to both the carbonyl and cyano termini. As a result of lowering the LUMO of the cyano group upon coordination of the Ti(III) species, the irreversible cyclization successfully proceeds without formation of the unstable iminyl radical intermediate. The ester group can also be activated by the coordination of Cp2TiPh, and aromatic ketones with an ester group at the γ position are cyclized to give the corresponding α-hydroxyketones.
Cp2TiPh-coordinated cyano and ester groups as efficient ketyl radical acceptors in the reductive radical cyclization of γ- And δ-cyano ketones and δ-keto esters
Yamamoto, Yoshihiko,Matsumi, Daisuke,Itoh, Kenji
, p. 875 - 876 (2007/10/03)
Cp2TiPh promotes the reductive radical cyclization of γ-and δ-cyano ketones and δketo esters to give α-hydroxycycloalkanones in moderate to good yields; the titanium reagent coordinates to both the ketone and the cyano or ester terminus, the LU
