5617-92-5Relevant academic research and scientific papers
Intramolecular nucleophilic capture of radical cations by tethered hydroxy functions
Roth, Heinz D.,Herbertz, Torsten,Sauers, Ronald R.,Weng, Hengxin
, p. 6471 - 6489 (2006)
A range of systems bearing hydroxy functions tethered to the molecular framework gives rise to a family of interesting radical cations, 5{radical dot}+-11{radical dot}+, upon electron transfer to photo-excited cyanoaromatics. Geraniol (5), nerol (6), citronellol (7), chrysanthemol (8), homochrysanthemol (9), trans-1-o-hydroxyphenyl-2-phenylcyclopropane (10), and endo-5-hydroxymethylnorbornene (11), generate a series of mono-, bi-, or tricyclic ethers via a series of four- to seven-membered transition states. Two of the radical cations, 5{radical dot}+ and 6{radical dot}+, undergo tandem cyclizations where 1,5- and/or 1,6-C-C cyclizations precede nucleophilic capture.
A diastereoselective synthesis of (1SR,3SR,7RS)-3-methyl-α- himachalene, the sex pheromone of the sandfly, Lutzomyia longipalpis (Diptera: Psychodidae)
Dufour, Samuel,Castets, Pascalie,Pickett, John A.,Hooper, Antony M.
, p. 5102 - 5108 (2012)
The sandfly, Lutzomyia longipalpis, vectors the causative agent of visceral leishmaniasis in the New World. The male-produced pheromone, (1S,3S,7R)-3-methyl-α-himachalene provides an opportunity for pest managing this pest problem by influencing the behaviour of the biting female. Previous syntheses of the pheromone have all focused on a late stage Diels-Alder cyclisation to generate the bicyclic cis-himachalene skeleton. By adopting a new retrosynthetic analysis that depends on an early stage Diels-Alder cyclisation, the number of steps has been reduced to ten, of which five are catalytic and so provides access to quantities suitable for field-scale experiments.
Diaminodiphosphine tetradentate ligand and ruthenium complex thereof, and preparation methods and applications of ligand and complex
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Paragraph 0316-0319, (2019/11/04)
The invention discloses a diaminodiphosphine tetradentate ligand and a ruthenium complex thereof, and preparation methods and applications of the ligand and the complex, and provides a ruthenium complex represented by a formula I, wherein L is a diaminodiphosphine tetradentate ligand represented by a formula II, and X and Y are respectively and independently chlorine ion, bromine ion, iodine ion,hydrogen negative ion or BH4. According to the present invention, the ruthenium complex exhibits excellent catalytic activity in the catalytic hydrogenation reactions of ester compounds, has high yield and high chemical selectivity, is compatible with conjugated and non-conjugated carbon-carbon double bond, carbon-carbon triple bond, epoxy, halogen, carbonyl and other functional groups, and hasgreat application prospects.
General and Phosphine-Free Cobalt-Catalyzed Hydrogenation of Esters to Alcohols
Shao, Zhihui,Zhong, Rui,Ferraccioli, Raffaella,Li, Yibiao,Liu, Qiang
supporting information, p. 1125 - 1130 (2019/10/22)
Catalytic hydrogenation of esters is essential for the sustainable production of alcohols in organic synthesis and chemical industry. Herein, we describe the first non-noble metal catalytic system that enables an efficient hydrogenation of non-activated esters to alcohols in the absence of phosphine ligands (with a maximum turnover number of 2391). The general applicability of this protocol was demonstrated by the high-yielding hydrogenation of 39 ester substrates including aromatic/aliphatic esters, lactones, polyesters and various pharmaceutical molecules.
Selective Deprotection of the Diphenylmethylsilyl (DPMS) Hydroxyl Protecting Group under Environmentally Responsible, Aqueous Conditions
Akporji, Nnamdi,Lieberman, Josh,Maser, Michael,Yoshimura, Masahiko,Boskovic, Zarko,Lipshutz, Bruce H.
, p. 5743 - 5747 (2019/11/11)
Two new methods for selective deprotection of diphenylmethylsilyl (DPMS) ethers are described. Unmasking can be achieved with either catalytic amounts of perfluoro-1-butanesulfonyl fluoride (a SuFEx reagent) under mild, aqueous micellar conditions, or using stoichiometric amounts of 18-crown-6 ether in aqueous ethanol.
Multicatalytic Stereoselective Synthesis of Highly Substituted Alkenes by Sequential Isomerization/Cross-Coupling Reactions
Romano, Ciro,Mazet, Clément
supporting information, p. 4743 - 4750 (2018/04/10)
Starting from readily available alkenyl methyl ethers, the stereoselective preparation of highly substituted alkenes by two complementary multicatalytic sequential isomerization/cross-coupling sequences is described. Both elementary steps of these sequences are challenging processes when considered independently. A cationic iridium catalyst was identified for the stereoselective isomerization of allyl methyl ethers and was found to be compatible with a nickel catalyst for the subsequent cross-coupling of the in situ generated methyl vinyl ethers with various Grignard reagents. The method is compatible with sensitive functional groups and a multitude of olefinic substitution patterns to deliver products with high control of the newly generated C=C bond. A highly enantioselective variant of this [Ir/Ni] sequence has been established using a chiral iridium precatalyst. A complementary [Pd/Ni] catalytic sequence has been optimized for alkenyl methyl ethers with a remote C=C bond. The final alkenes were isolated with a lower level of stereocontrol. Upon proper choice of the Grignard reagent, we demonstrated that C(sp2) - C(sp2) and C(sp2) - C(sp3) bonds can be constructed with both systems delivering products that would be difficult to access by conventional methods.
COMPLEX CATALYSTS BASED ON AMINO-PHOSPHINE LIGANDS FOR HYDROGENATION AND DEHYDROGENATION PROCESSES
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Page/Page column 38; 39, (2014/09/29)
The present application discloses novel PWNN and PWNWP metal catalysts for organic chemical syntheses including hydrogenation (reduction) of unsaturated compounds or dehydrogenation of substrates. The range of hydrogenation substrate compounds includes esters, lactones, enals, enones, enolates, oils and fats, resulting in alcohols, enols, diols, and triols as reaction products. The catalysts of current application can be used to catalyze a hydrogenation reaction under solvent free conditions. The present catalysts also allow the hydrogenation to proceed without added base, and it can be used in place of the conventional reduction methods employing hydrides of the main-group elements. Furthermore, the catalysts of the present application can catalyze a dehydrogenation reaction under homogenous and/or acceptorless conditions. As such, the catalysts provided herein can be useful in substantially reducing cost and improving the environmental profile of manufacturing processes for a variety of chemicals.
Chrysanthemyl diphosphate synthase operates in planta as a bifunctional enzyme with chrysanthemol synthase activity
Yang, Ting,Gao, Liping,Hu, Hao,Stoopen, Geert,Wang, Caiyun,Jongsma, Maarten A.
, p. 36325 - 36335 (2015/02/19)
Chrysanthemyl diphosphate synthase (CDS) is the first path-way-specific enzyme in the biosynthesis of pyrethrins, the most widely used plant-derived pesticide. CDS catalyzes c1′-2-3 cyclopropanation reactions of two molecules of dimethylallyl diphosphate (DMAPP) to yield chrysanthemyl diphosphate (CPP). Three proteins are known to catalyze this cyclopropanation reaction of terpene precursors. Two of them, phytoene and squalene synthase, are bifunctional enzymes with both prenyltransferase and terpene synthase activity. CDS, the other member, has been reported to perform only the prenyltransferase step. Here we show that the NDXXD catalytic motif of CDS, under the lower substrate conditions prevalent in plants, also catalyzes the next step, converting CPP into chrysanthemol by hydrolyzing the diphosphate moiety. The enzymatic hydrolysis reaction followed conventional Michaelis-Menten kinetics, with a Km value for CPP of 196 μM. For the chrysanthemol synthase activity, DMAPP competed with CPP as substrate. The DMAPP concentration required for half-maximal activity to produce chrysanthemol was ～100 μM, and significant substrate inhibition was observed at elevated DMAPP concentrations. The N-terminal peptide of CDS was identified as a plastid-targeting peptide. Transgenic tobacco plants overexpressing CDS emitted chrysanthemol at a rate of 0.12-0.16 μg h-1 g-1 fresh weight. We propose that CDS should be renamed a chrysanthemol synthase utilizing DMAPP as substrate.
An Inexpensive Air-Stable Titanium-Based System for the Conversion of Esters to Primary Alcohols
Reding, Matthew T.,Buchwald, Stephen L.
, p. 7884 - 7890 (2007/10/03)
Polymethylhydroxiloxane, when combined with titanium(IV) isopropoxide, provides a convenient system for the conversion of esters to the corresponding primary alcohols in the presence of a wide range of functional groups.Reactions are carried out as mixtures of the neat reaction components; workup with aqueous alkaline THF affords primary alcohols in good to excellent yields.The system tolerates primary alkyl bromides and iodides, olefins, epoxides, and alkynes.Steric differentiation of methyl and tert-butyl esters is also possible.The results observed in the parent and related reactions argue against pathways involving Lewis-acid catalysis and anionic hydridosilicate-mediated reductions, and instead support a neutral titanium hydride complex or strongly associated titanium/silane complex as the active reducing agent.
