2216-52-6Relevant academic research and scientific papers
Alkylation of acylmetalates with alkyl halides to prepare Fischer carbene complexes: An improved protocol
Nandi, Bappaditya,Sinha, Surajit
, p. 106 - 113 (2011)
Alkoxy Fischer carbene complexes have been synthesized by alkylation of lithium acylmetalates with alkyl halides in the presence of catalytic amount (5-10 mol %) of n-tetrabutylammonium bromide (n-Bu4NBr) restricting the temperature below 55 °C to minimize decomposition of the product. The reaction occurs in a biphasic condition involving water and alkyl halide. The effect of cesium on this alkylation reaction has been studied. The presence of a radical quencher, di-tert-butyl phenol, neither affects the yield nor leads to the formation of dimer of di-tert-butyl phenol, which rules out the possibility of radical pathway mechanism. The kinetic study and the 1H NMR spectra of products suggest an SN2 pathway particularly involving alkyl halides.
Biotransformation of (-)-menthone by human liver microsomes
Miyazawa, Mitsuo,Nakanishi, Kyousuke
, p. 1259 - 1261 (2006)
The aim of the current study was to investigate the metabolism of (-)-menthone by liver microsomes of humans. (-)-Menthone (1) was metabolized to (+)-neomenthol (2) (3-reduction) and 7-hydroxymenthone (3) by human liver microsomes. The metabolites formed were analyzed on GC and GC-MS. Kinetic analysis showed that Km and Vmax values for the metabolized (-)-menthone to respective (+)-neomenthol and 7-hydroxymenthone by liver microsomes of human sample HG70 were 0.37 mM and 4.91 nmol/min/mg protein and 0.07 mM and 0.71 nmol/min/mg protein.
Revision of the stereochemistry of elisabethatriene, a putative biosynthetic intermediate of pseudopterosins
Nasuda, Masayuki,Ohmori, Miho,Ohyama, Kiyoshi,Fujimoto, Yoshinori
, p. 681 - 685 (2012)
In the past, we have questioned the accuracy of the stereochemistry of elisabethatriene, a putative biosynthetic intermediate of pseudopterosins, in light of the configuration of elisabethatrienol isolated from Pseudopterogorgia elisabethae, which was represented as 1S,4R,9S,11S. We have reinvestigated the stereochemistry of elisabethatriene. Elisabethatriene with the reported 1S,4R,9R,11S configuration was synthesized starting from (-)-isopulegol in its enantiomeric form. The 1H- and 13C-NMR data of the synthesized compound differed from those reported for elisabethatriene. In addition to the fact that elisabethatriene is converted into pseudopterosins, this finding has allowed us to propose that elisabethatriene should have the 1S,4R,9S,11S stereochemistry, which is identical to that of elisabethatrienol.
Continuous synthesis of menthol from citronellal and citral over Ni-beta-zeolite-sepiolite composite catalyst
Er?nen, Kari,M?ki-Arvela, P?ivi,Martinez-Klimov, Mark,Muller, Joseph,Murzin, Dmitry Yu.,Peurla, Markus,Simakova, Irina,Vajglova, Zuzana
, (2022/04/03)
One-pot continuous synthesis of menthols both from citronellal and citral was investigated over 5 wt% Ni supported on H-Beta-38-sepiolite composite catalyst at 60–70 °C under 10–29 bar hydrogen pressure. A relatively high menthols yield of 53% and 49% and stereoselectivity to menthol of 71–76% and 72–74% were obtained from citronellal and citral respectively at the contact time 4.2 min, 70 °C and 20 bar. Citral conversion noticeably decreased with time-on-stream under 10 and 15 bar of hydrogen pressure accompanied by accumulation of citronellal, the primary hydrogenation product of citral, practically not affecting selectivity to menthol. A substantial amount of defuctionalization products observed during citral conversion, especially at the beginning of the reaction (ca. 1 h), indicated that all intermediates could contribute to formation of menthanes. Ni/H-Beta-38-sepiolite composite material prepared by extrusion was characterized by TEM, SEM, XPS, XRD, ICP-OES, N2 physisorption and FTIR techniques to perceive the interrelation between the physico-chemical and catalytic properties.
Heterogeneous Hydroxyl-Directed Hydrogenation: Control of Diastereoselectivity through Bimetallic Surface Composition
Shumski, Alexander J.,Swann, William A.,Escorcia, Nicole J.,Li, Christina W.
, p. 6128 - 6134 (2021/05/29)
Directed hydrogenation, in which product selectivity is dictated by the binding of an ancillary directing group on the substrate to the catalyst, is typically catalyzed by homogeneous Rh and Ir complexes. No heterogeneous catalyst has been able to achieve equivalently high directivity due to a lack of control over substrate binding orientation at the catalyst surface. In this work, we demonstrate that Pd-Cu bimetallic nanoparticles with both Pd and Cu atoms distributed across the surface are capable of high conversion and diastereoselectivity in the hydroxyl-directed hydrogenation reaction of terpinen-4-ol. We postulate that the OH directing group adsorbs to the more oxophilic Cu atom while the olefin and hydrogen bind to adjacent Pd atoms, thus enabling selective delivery of hydrogen to the olefin from the same face as the directing group with a 16:1 diastereomeric ratio.
Preparation of Neutral trans - Cis [Ru(O2CR)2P2(NN)], Cationic [Ru(O2CR)P2(NN)](O2CR) and Pincer [Ru(O2CR)(CNN)P2] (P = PPh3, P2= diphosphine) Carboxylate Complexes and their Application in the Catalytic Carbonyl Compounds Reduction
Baldino, Salvatore,Giboulot, Steven,Lovison, Denise,Nedden, Hans Günter,P?thig, Alexander,Zanotti-Gerosa, Antonio,Zuccaccia, Daniele,Ballico, Maurizio,Baratta, Walter
, p. 1086 - 1103 (2021/05/06)
The diacetate complexes trans-[Ru(κ1-OAc)2(PPh3)2(NN)] (NN = ethylenediamine (en) (1), 2-(aminomethyl)pyridine (ampy) (2), 2-(aminomethyl)pyrimidine (ampyrim) (3)) have been isolated in 76-88% yield by reaction of [Ru(κ2-OAc)2(PPh3)2] with the corresponding nitrogen ligands. The ampy-type derivatives 2 and 3 undergo isomerization to the thermodynamically most stable cationic complexes [Ru(κ1-OAc)(PPh3)2(NN)]OAc (2a and 3a) and cis-[Ru(κ1-OAc)2(PPh3)2(NN)] (2b and 3b) in methanol at RT. The trans-[Ru(κ1-OAc)2(P2)2] (P2 = dppm (4), dppe (5)) compounds have been synthesized from [Ru(κ2-OAc)2(PPh3)2] by reaction with the suitable diphosphine in toluene at 95 °C. The complex cis-[Ru(κ1-OAc)2(dppm)(ampy)](6) has been obtained from [Ru(κ2-OAc)2(PPh3)2] and dppm in toluene at reflux and reaction with ampy. The derivatives trans-[Ru(κ1-OAc)2P2(NN)] (7-16; NN = en, ampy, ampyrim, 8-aminoquinoline; P2 = dppp, dppb, dppf, (R)-BINAP) can be easily synthesized from [Ru(κ2-OAc)2(PPh3)2] with a diphosphine and treatment with the NN ligands at RT. Alternatively these compounds have been prepared from trans-[Ru(OAc)2(PPh3)2(NN)] by reaction with the diphosphine in MEK at 50 °C. The use of (R)-BINAP affords trans-[Ru(κ1-OAc)2((R)-BINAP)(NN)] (NN = ampy (11), ampyrim (15)) isolated as single stereoisomers. Treatment of the ampy-type complexes 8-15 with methanol at RT leads to isomerization to the cationic derivatives [Ru(κ2-OAc)P2(NN)]OAc (8a-15a; NN = ampy, ampyrim; P2 = dppp, dppb, dppf, (R)-BINAP). Similarly to 2, the dipivalate trans-[Ru(κ1-OPiv)2(PPh3)2(ampy)] (18) is prepared from [Ru(κ2-OPiv)2(PPh3)2] (17) and ampy in CHCl3. The pincer acetate [Ru(κ1-OAc)(CNNOMe)(PPh3)2] (19) has been synthesized from [Ru(κ2-OAc)2(PPh3)2] and HCNNOMe ligand in 2-propanol with NEt3 at reflux. In addition, the dppb pincer complexes [Ru(κ1-OAc)(CNN)(dppb)] (CNN = AMTP (20), AMBQPh (21)) have been obtained from [Ru(κ2-OAc)2(PPh3)2], dppb, and HAMTP or HAMBQPh with NEt3, respectively. The acetate NN and pincer complexes are active in transfer hydrogenation with 2-propanol and hydrogenation with H2 of carbonyl compounds at S/C values of up to 10000 and with TOF values of up to 160000 h-1.
Synthesis of new mixed (-)-menthylalkyltin dihydrides. stereoselective reduction of chiral and prochiral ketones
Terraza, V. Fabricio,Gerbino, Darío C.,Podestá, Julio C.
, (2021/02/06)
This paper reports de synthesis of a series of (-)-menthylalkyltin dihydrides, (-)-MenRSnH2 (R = Me, n-Bu, i-Pr, t-Bu, Neophyl), starting from (-)-menthyltrimethyltin. The new (-)-menthylalkyltin dihydrides 12–16 were used in a study on the stereoselective reduction of chiral (-)-menthone under different reaction conditions. Also the results obtained in the reductions of prochiral acetophenone (27) and 2-acetylnaphthalene (28), with (-)-menthylmethyl- (12) and (-)-menthyli-propyltin (14) dihydrides are informed. Some physical properties as well as full 1H-, 13C-, and 119Sn NMR data of the new organotin compounds are informed.
Continuous flow synthesis of menthol: Via tandem cyclisation-hydrogenation of citronellal catalysed by scrap catalytic converters
Zuliani, Alessio,Cova, Camilla Maria,Manno, Roberta,Sebastian, Victor,Romero, Antonio A.,Luque, Rafael
, p. 379 - 387 (2020/02/13)
A continuous flow synthesis of menthol starting from citronellal catalysed by scrap catalytic converters is reported. The reaction was conducted in a tandem system connecting in series two catalytic systems, with the first having Lewis acid properties (favouring the cyclisation of citronellal to isopulegols) and the second having hydrogenation catalytic activity (catalysing the hydrogenation of isopulegols to menthols). A Lewis acid catalyst was prepared by supporting iron oxide nanoparticles over a waste material, i.e. the ceramic core of scrap catalytic converters (SCATs) via a microwave assisted method. Most importantly, SCATs, containing a low residual noble metal content, could be directly employed in the second step as hydrogenation catalysts. The reaction was performed studying the influence on the yield and selectivity to (-)-menthol of various reaction parameters (T, p and flow rate). Under the best reaction conditions (at a flow rate of 0.1 mL min-1 and at 373 K and 413 K for cyclisation and hydrogenation steps respectively) a conversion of >99% of (+)-citronellal to (-)-menthol with 77% final yield was achieved.
Chemoselective Oxidation of Equatorial Alcohols with N-Ligated λ3-Iodanes
Mikhael, Myriam,Adler, Sophia A.,Wengryniuk, Sarah E.
supporting information, p. 5889 - 5893 (2019/08/26)
The site-selective and chemoselective functionalization of alcohols in complex polyols remains a formidable synthetic challenge. Whereas significant advancements have been made in selective derivatization at the oxygen center, chemoselective oxidation to the corresponding carbonyls is less developed. In cyclic systems, whereas the selective oxidation of axial alcohols is well known, a complementary equatorial selective process has not yet been reported. Herein we report the utility of nitrogen-ligated (bis)cationic λ3-iodanes (N-HVIs) for alcohol oxidation and their unprecedented levels of selectivity for the oxidation of equatorial over axial alcohols. The conditions are mild, and the simple pyridine-ligated reagent (Py-HVI) is readily synthesized from commercial PhI(OAc)2 and can be either isolated or generated in situ. Conformational selectivity is demonstrated in both flexible 1,2-substituted cyclohexanols and rigid polyol scaffolds, providing chemists with a novel tool for chemoselective oxidation.
Flat and Efficient H CNN and CNN Pincer Ruthenium Catalysts for Carbonyl Compound Reduction
Giboulot, Steven,Baldino, Salvatore,Ballico, Maurizio,Figliolia, Rosario,P?thig, Alexander,Zhang, Shuanming,Zuccaccia, Daniele,Baratta, Walter
, p. 1127 - 1142 (2019/03/14)
The bidentate HCNN dicarbonyl ruthenium complexes trans,cis-[RuCl2(HCNN)(CO)2] (1-3) and trans,cis-[RuCl2(ampy)(CO)2] (1a) were prepared by reaction of [RuCl2(CO)2]n with 1-[6-(4′-methylphenyl)pyridin-2-yl]methanamine, benzo[h]quinoline (HCNN), and 2-(aminomethyl)pyridine (ampy) ligands. Alternatively, the derivatives 1-3 were obtained from the reaction of RuCl3 hydrate with HCO2H and HCNN. The pincer CNN cis-[RuCl(CNN)(CO)2] (4) was isolated from 1 by reaction with NEt3. The monocarbonyl complexes trans-[RuCl2(HCNN)(PPh3)(CO)] (5-7) were synthesized from [RuCl2(dmf)(PPh3)2(CO)] and HCNN ligands, while the diacetate trans-[Ru(OAc)2(HCNN)(PPh3)(CO)] (8) was obtained from [Ru(OAc)2(PPh3)2(CO)]. Carbonylation of cis-[RuCl(CNN)(PPh3)2] with CO afforded the pincer derivatives [RuCl(CNN)(PPh3)(CO)] (9-11). Treatment of 9 with Na[BArf]4 and PPh3 gave the cationic complex trans-[Ru(CNN)(PPh3)2(CO)][BArf4] (12). The dicarbonyl derivatives 1-4, in the presence of PPh3 or PCy3, and the monocarbonyl complexes 5-12 catalyzed the transfer hydrogenation (TH) of acetophenone (a) in 2-propanol at reflux (S/C = 1000-100000 and TOF up to 100000 h-1). Compounds 1-3, with PCy3, and 6 and 8-10 were proven to catalyze the TH of carbonyl compounds, including α,β-unsaturated aldehydes and bulky ketones (S/C and TOF up to 10000 and 100000 h-1, respectively). The derivatives 1-3 with PCy3 and 5 and 6 catalyzed the hydrogenation (HY) of a (H2, 30 bar) at 70 °C (S/C = 2000-10000). Complex 5 was active in the HY of diaryl ketones and aryl methyl ketones, leading to complete conversion at S/C = 10000.
