Tetra-n-propylammonium Perruthenate Research Articles

Catalytic [2+2+2] Tandem Cyclization with Alkyl Substituted Methylene Malonate Enabling Concise Total Synthesis of Four Malagasy Alkaloids

Catalytic [2+2+2] Tandem Cyclization with Alkyl Substituted Methylene Malonate Enabling Concise Total Synthesis of Four Malagasy Alkaloids

NMO⋅TPB: a selectivity variation on the Ley-Griffith TPAP oxidation.

A non-hygroscopic tetraphenylborate salt of N-methylmorpholine-N-oxide (NMO) is reported (NMO⋅TPB), which modulates the standard Ley-Griffith oxidation such that benzylic and allylic alcohols are oxidised selectively. An attractive feature of this new protocol is that anhydrous conditions are not required for this selective tetra-n-propylammonium perruthenate (TPAP) oxidation, superseding the requirement of molecular sieves.

The grounds for the activity of TPAP in oxidation catalysis in supercritical carbon dioxide when confined in hybrid fluorinated silica matrices

Fluorinated organo-silica gels doped with tetra-n-propylammonium perruthenate (TPAP) are excellent catalysts for the aerobic oxidative dehydrogenation of alcohols in supercritical CO2 (scCO2). Their activity and stability are subtly dictated by structure, depending on the degree of fluorination and on the length of the fluoroalkyl chain linked to the silica network. Such dependence reflects the hydrophilic-hydrophobic balance (HHB) of the matrix, as evaluated by diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy. The remarkable correlation between the materials' HHB and reactivity provides a finding of general validity for reaction-controlled mechanisms, which opens the route to the synthesis of second generation sol-gel entrapped catalysts for the production of fine chemicals in scCO2.

Tetra-N-propylammonium Perruthenate (TPAP)

The crystalline, non-volatile and air-stable material tetra-N-propylammonium perruthenate (TPAP) is an important commercial catalytic oxidant, mostly used in natural products synthesis due to its ease of use, excellent performance and versatility. [1] In 1987, Ley and co-workers first introduced TPAP as a readily soluble, nonvolatile, air-stable oxidant for alcohols. [1] [2] It behaves as an overall three-electron oxidant for a wide range of multifunctional species. The full potential of TPAP was revealed when its catalytic behavior with N-methylmorpholine N-oxide (NMO) as terminal oxidant was uncovered. [3] It is stable at room temperature and may be stored for long periods under low-temperature condition. The TPAP-O2 oxidizing system meets several principles of Green Chemistry [4] and raises the prospect for industrial oxidations because of (i) its applicability in oxidation of a wide range of alcohols, (ii) its potential as terminal oxidant with air, (iii) the simple separation of the catalyst from the products, and (iv) its chemoselectivity and tolerance against many functional groups. The catalyst is inert towards double bonds, polyenes, enones, halides, cyclopropanes, epoxides, acetals, esters, amides, lactones, amines, peroxides, and catechols. Clean oxidation of alcohols occurs with TPAP in systems where competitive β-elimination poses a problem with other oxidants. [5] In addition to that, oxidation with TPAP can be achieved without racemization of the adjacent stereogenic α-centers and without double-bond migration. [4]

FluoRuGel: a versatile catalyst for aerobic alcohol oxidation in supercritical carbon dioxide

FluoRuGel--a hybrid fluorinated silica glass doped with TPAP (tetra-n-propylammonium perruthenate)--is a versatile catalyst for the aerobic oxidation of different alcohols in dense phase CO(2) with marked stabilization and activity enhancement of perruthenate upon its confinement in the sol-gel fluorinated silica matrix. A brief competitive analysis shows large potential rewards.

Total Synthesis of (+)‐Batzelladine A and (−)‐Batzelladine D, and Identification of Their Target Protein

Asymmetric total synthesis of batzelladine A (1) and batzelladine D (2) has been achieved. Our synthesis of batzelladines features 1) stereoselective construction of the cyclic guanidine system by means of successive 1,3-dipolar cycloaddition reaction and subsequent cyclization, 2) direct esterification of the bicyclic carboxylic acid 35 with the guanidine alcohol 8 or 59 to construct the whole carbon skeleton of batzelladines, and 3) one-step formation of the alpha,beta-unsaturated aldehyde 53 from the primary alcohol 47 with tetra-n-propylammoniumperruthenate (TPAP), providing an efficient route to the left-hand bicyclic guanidine alcohol of batzelladine A (1). With the synthetic compounds 1 and 2 in hand, their target protein was examined by using immobilized CD4 and gp120 affinity gels. The results indicated that batzelladines A (1) and D (2) bind specifically to CD4.

Total Synthesis of Dictyodendrin B

A concise total synthesis of dictyodendrin B (1) is reported, a scarce marine alkaloid endowed with promising telomerase inhibitory activity. Key steps of the chosen route are a reductive cyclization of ketoamide 11 to indole 12 mediated by low-valent titanium (from TiCl3 and KC8) followed by a photochemical 6pi-electrocyclization, which was performed in the presence of Pd/C and nitrobenzene to effect concomitant dehydrogenation/aromatization of the product initially formed. Regioselective bromination of the resulting pyrrolocarbazole 13 followed by lithium/bromine exchange and quenching of the resulting organolithium species with p-methoxybenzaldehyde installed the side chain at C2. Oxidation of the benzylic alcohol 15 thus obtained to ketone 17 was best achieved with catalytic amounts of tetra-n-propylammonium perruthenate (TPAP) and N-methylmorpholine-N-oxide (NMO) in dilute CH2Cl2 solution to avoid the formation of undue amounts of the unsymmetrical dimer 16. Ketone 17 was elaborated into the natural product by selective cleavage of the isopropyl ether with BCl3, introduction of the sulfate moiety with the aid of trichloroethyl chlorosulfuric acid ester, deprotection of all lateral methyl ether groups, and final reductive cleavage of the trichloroethyl ester moiety. The spectroscopic data of synthetic dictyodendrin B thus formed matched those of an authentic sample in all regards. Moreover, it was shown that global deprotection of the peripheral -OH groups in pyrrolo[2,3-c]carbazole 13 is accompanied by spontaneous air-oxidation to form the quinone core of dictyodendrin C.

Dynamic Catalysis in Aerobic Oxidation by Sol-Gel Living Materials

The catalytic activity of hybrid organic–inorganic silica glasses doped with the ruthenium species tetra-n-propylammonium perruthenate (TPAP) in the aerial oxidation of alcohols to carbonyl compounds, either in toluene or in dense-phase CO2, substantially increases with time several months after the xerogels' preparation, yielding the most active ruthenium-based aerobic-oxidation catalysts reported thus far. The doped sol–gels are living materials, and an explanation of the observed reactivity enhancement is given, which is thought to have general validity for future applications to a wide variety of relevant heterogeneous processes.

Alcohols Oxidation with Hydrogen Peroxide Promoted by TPAP‐Doped Ormosils.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Alcohols oxidation with hydrogen peroxide promoted by TPAP-doped ormosils

Organically modified silica gels doped with TPAP (tetra- n-propylammonium perruthenate) are effective catalysts for the oxidation of alcohols by hydrogen peroxide at room temperature, provided that the oxidant H 2O 2 solution is added slowly. The effect of the surface catalyst polarity is the opposite of that found in aerobic alcohols oxidation and is consistent with the polar nature of the primary oxidant.

Fluorinated Silica Gels Doped with TPAP as Effective Aerobic Oxidation Catalysts in Dense Phase Carbon Dioxide

AbstractHybrid organic‐inorganic fluorinated silica glasses doped with the ruthenium species TPAP (tetra‐n‐propylammonium perruthenate) are effective catalysts for the aerial oxidation of benzyl alcohol to benzaldehyde in dense phase CO2. Moderate silica fluorination (10%) by short‐chain fluoroalkyl‐containing monomers in the sol‐gel polycondensation with TMOS affords highly active catalysts which at 75 °C and 220 bar selectively dehydrogenate the alcohol with oxygen as primary oxidant. Both the activity and the stability of the fluorinated materials vary with the degree of fluorination and the nature of the fluoroalkyl residue attached to the silica polymeric network. An explanation of the behaviour of doped sol‐gel oxides in supercritical carbon dioxide is proposed which is thought to be of general validity for future practical applications to heterogeneously catalysed aerobic oxidations eliminating the current need for both organic solvents and stoichiometric oxidants.

A Sequential Tetra‐n‐propylammonium Perruthenate (TPAP)—Wittig Oxidation Olefination Protocol.

AbstractFor Abstract see ChemInform Abstract in Full Text.

The Effects of Material Properties on the Activity of Sol‐Gel Entrapped Perruthenate under Supercritical Conditions

AbstractSilica gels organically modified and doped with the ruthenium species tetra‐n‐propylammonium perruthenate (TPAP) are leach‐proof, selective catalysts for the aerobic oxidation of alcohols to carbonyl compounds with dioxygen at low pressure in compressed carbon dioxide. The catalytic sol‐gels are recyclable and the correlation between the reactivity of the materials and their surface polarity and textural properties suggests valuable information on the chemical behaviour of sol‐gel entrapped silica catalysts in oxidation catalysis which is of relevant interest considering the importance of heterogeneous oxidative dehydrogenation of alcohols in fine chemistry. An explanation of the structure‐activity relationship is proposed to provide guidelines for the further development of efficient solid oxidation catalysts for conversions in supercritical carbon dioxide.

Tailoring the catalytic performance of sol-gel-encapsulated tetra-n-propylammonium perruthenate (TPAP) in aerobic oxidation of alcohols.

Sol-gel nanohybrid silica particles organically modified and doped with the ruthenium species tetra-n-propylammonium perruthenate (TPAP) are highly efficient catalysts for the selective oxidation of alcohols to carbonyl groups with O(2) at low pressure in toluene. The materials are easily prepared by a one-step sol-gel process, and their catalytic performance can be optimised by tailoring the conditions of their synthesis by hydrolytic co-polycondensation of tetramethoxysilane (TMOS) and alkyltrimethoxysilanes R-Si(OMe)(3) in the presence of TPAP. Eventually, heterogeneous catalysts considerably more active than the unsupported perruthenate were obtained, while also being leach-proof and recyclable. The correlation between the materials' activity, surface polarity and textural properties suggests valuable information on the chemical behaviour of sol-gel catalytic materials in oxidation catalysis; this is of interest in view of the importance of efficient solid catalysts for the selective oxidation of alcohols with O(2).

A sequential tetra-n-propylammonium perruthenate (TPAP)–Wittig oxidation olefination protocol

A convenient sequential oxidation–olefination protocol is reported using tetra-n-propylammonium perruthenate (TPAP) as oxidant and phosphonium salts as olefin source. The oxidation reaction mixture is added directly to the phosphorane facilitating an efficient method for this transformation that avoids work-up of potentially sensitive aldehyde intermediates.

Reductive alkylation of anhydrides and lactones: direct access to monosubstituted lactones

Reductive alkylation of anhydrides (1 equiv) with a 2:0.25 mixture of Grignard reagent and Zn(BH 4) 2 afforded monosubstituted lactones in moderate yields. The same sequence applied to unsubstituted lactones gave monoalkylated diols, which were further selectively oxidised with tetra- n-propylammonium perruthenate (TPAP) into the expected monoalkylated lactones.

New recyclable catalysts for aerobic alcohols oxidation: sol-gel ormosils doped with TPAP

Novel nanoporous materials have been prepared that are recyclable catalysts for the aerobic oxidation of activated and non-activated alcohols. The catalysts are organically modified silicas (ormosils) doped with tetra- n-propylammonium perruthenate (TPAP) via the sol-gel process. Hydrophobicity and flexibility of the sol-gel cages were crucial in promoting catalysis.

Tetra-n-propyl Ammonium Perruthenate (TPAP) - An Efficient and Selective Reagent for Oxidation Reactions in Solution and on the Solid Phase

Journal für praktische ChemieVolume 342, Issue 7 p. 728-730 Reagent Tetra-n-propyl Ammonium Perruthenate (TPAP) — An Efficient and Selective Reagent for Oxidation Reactions in Solution and on the Solid Phase Peter Langer Dr., Corresponding Author Peter Langer Dr. plangercommat;uni-goettingen.de Göttingen, Institut für Organische Chemie der Georg-August-UniversitätGeorg-August-Universität Göttingen, Institut für Organische Chemie, Tammannstraße 2, D-37077 Göttingen, Fax: Internat. code (0) 551–399475Search for more papers by this author Peter Langer Dr., Corresponding Author Peter Langer Dr. plangercommat;uni-goettingen.de Göttingen, Institut für Organische Chemie der Georg-August-UniversitätGeorg-August-Universität Göttingen, Institut für Organische Chemie, Tammannstraße 2, D-37077 Göttingen, Fax: Internat. code (0) 551–399475Search for more papers by this author First published: 17 August 2000 https://doi.org/10.1002/1521-3897(200009)342:7<728::AID-PRAC728>3.0.CO;2-RCitations: 26AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article.Citing Literature Volume342, Issue7September 2000Pages 728-730 RelatedInformation

Tetra-n-propyl Ammonium Perruthenate (TPAP) - An Efficient and Selective Reagent for Oxidation Reactions in Solution and on the Solid Phase

Journal für praktische ChemieVolume 342, Issue 7 p. 728-730 Reagent Tetra-n-propyl Ammonium Perruthenate (TPAP) — An Efficient and Selective Reagent for Oxidation Reactions in Solution and on the Solid Phase Peter Langer Dr., Corresponding Author Peter Langer Dr. plangercommat;uni-goettingen.de Göttingen, Institut für Organische Chemie der Georg-August-UniversitätGeorg-August-Universität Göttingen, Institut für Organische Chemie, Tammannstraße 2, D-37077 Göttingen, Fax: Internat. code (0) 551–399475Search for more papers by this author Peter Langer Dr., Corresponding Author Peter Langer Dr. plangercommat;uni-goettingen.de Göttingen, Institut für Organische Chemie der Georg-August-UniversitätGeorg-August-Universität Göttingen, Institut für Organische Chemie, Tammannstraße 2, D-37077 Göttingen, Fax: Internat. code (0) 551–399475Search for more papers by this author First published: 17 August 2000 https://doi.org/10.1002/1521-3897(200009)342:7<728::AID-PRAC728>3.0.CO;2-RCitations: 26AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article.Citing Literature Volume342, Issue7September 2000Pages 728-730 RelatedInformation

Synthesis of pyrrolo[2,1- c][1,4]benzodiazepine antibiotics: Oxidation of cyclic secondary amine with TPAP

A facile procedure for the preparation of the imine form of the pyrrolo[2,1- c][1,4]-benzodiazepine ring system by the oxidation of cyclic secondary amine with catalytic amounts of tetra-n-propylammonium perruthenate (TPAP) and N-methylmorpholine N-oxide (NMO) as a co-oxidant is described. This oxidative method is devoid of side-products and is thus a significant improvement over the Swern oxidation previously reported.