- A rhodium peroxido complex in Mono-, Di-, and peroxygenation reactions
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A versatile peroxido complex: The rhodium peroxido complex 1, which can be prepared from 2 and dioxygen, participates in mono-oxygenation of a phosphine and dioxygenation of tetrakis(dimethylamino)ethylene to give, respectively, phosphine oxide and a urea derivative, while peroxygenation of 9,10-dimethylanthracene to yield the anthracene endoperoxide takes place in the presence of dioxygen and substoichiometric amounts of 1 (see scheme). Copyright
- Meier, Gregor,Braun, Thomas
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Read Online
- Studies of reaction of tetramethylthiourea with hydrogen peroxide: evidence of formation of tetramethylthiourea monoxide as a key intermediate of the reaction
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The reaction between tetramethylthiourea (TMTU) and hydrogen peroxide was studied by UV–VIS spectroscopy, ESI mass spectrometry, 1H NMR, cyclic voltammetry and surface-enhanced Raman scattering. We found that the reaction includes two consecutive steps, that is, (i) an oxidation of TMTU to TMTU monoxide (TMTMO) and (ii) further oxidation of TMTU monoxide to tetramethylurea (TMU) and sulfate. The second step is complex and seems to include extrusion of sulfur monoxide (SO). Density functional theory calculations were employed on tetramethylthiourea oxide models in order to underline differences between monoxide and di- and trioxides. Calculations predict that the TMTMO structure can be best explained as an adduct of thiourea with an oxygen atom (═S–>O).
- Dereven’kov, Ilia A.,Ivlev, Pavel A.,Salnikov, Denis S.,Bischin, Cristina,Attia, Amr A. A.,Silaghi-Dumitrescu, Radu,Makarov, Sergei V.
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- On the exchange reaction,, using hexafluoroacetone
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The reaction of λ3-phospha-diazetidin-thione, 1 with hexafluoroacetone (HFA) furnished not only the expected addition product, the λ5P-perfluoropinacolyl phosphorane, 2. In addition, HFA was observed to cause {A figure is presented} exchange in 2, and exclusive formation of a urea derivative, 3, was noted upon prolonged interaction of HFA with 2. Likewise, N,N,N′,N′,-tetramethylthiourea, 1, was found to be converted to N,N,N′,N′-tetrarmethylurea, 5, by HFA. The reactions were followed by 1H-, 13C-, 19F- and 31P-n.m.r. spectroscopy.
- Gruber, Matthias,Schmutzler, Reinhard
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- Copper(II) chloride-catalyzed oxidative carbonylation of glycerol to glycerol carbonate
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A systematic study on copper(II) as catalyst for the synthesis of glycerol carbonate via oxidative carbonylation is here reported for the first time. Copper(II) chloride has been found to efficiently promote the process under homogeneous conditions treating glycerol with CO:O2 (Ptot = 4 MPa; P(O2) = 0.7 MPa), in DMA at 130 C and in the presence of pyridine as co-catalyst. Excellent conversions (>92%) and selectivities (>93%) are obtained in relatively short reaction times (3-4 h) also with copper(II) complexes. The catalyst overall TON is evaluated and new experimental evidences are provided allowing significant advancements in the mechanism comprehension.
- Casiello, Michele,Monopoli, Antonio,Cotugno, Pietro,Milella, Antonella,Dell'Anna, Maria Michela,Ciminale, Francesco,Nacci, Angelo
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- Amine-Responsive Disassembly of AuI–CuI Double Salts for Oxidative Carbonylation
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A sensitive amine-responsive disassembly of self-assembled AuI-CuI double salts was observed and its utilization for the synergistic catalysis was enlightened. Investigation of the disassembly of [Au(NHC)2][CuI2] revealed the contribution of Cu-assisted ligand exchange of N-heterocyclic carbene (NHC) by amine in [Au(NHC)2]+ and the capacity of [CuI2]? on the oxidative step. By integrating the implicative information coded in the responsive behavior and inherent catalytic functions of d10 metal complexes, a catalyst for the oxidative carbonylation of amines was developed. The advantages of this method were clearly reflected on mild reaction conditions and the significantly expanded scope (51 examples); both primary and steric secondary amines can be employed as substrates. The cooperative reactivity from Au and Cu centers, as an indispensable prerequisite for the excellent catalytic performance, was validated in the synthesis of (un)symmetric ureas and carbamates.
- Cao, Yanwei,Yang, Jian-Gong,Deng, Yi,Wang, Shengchun,Liu, Qi,Shen, Chaoren,Lu, Wei,Che, Chi-Ming,Chen, Yong,He, Lin
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supporting information
p. 2080 - 2084
(2019/12/24)
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- Tetramethylurea and preparation method thereof
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The invention provides tetramethylurea and a preparation method thereof. The preparation method comprises the following steps that S1, dimethylamine and triphosgene are provided; S2, the dimethylamineand the triphosgene react to generate the tetramethylurea. According to the preparation method of the tetramethylurea, the dimethylamine and the triphosgene are used as raw materials, the dimethylamine can be a dimethylamine water solution or dimethylamine gas, and the triphosgene can be triphosgene itself or an organic triphosgene solution. The preparation method is simple in operation, high inproduct yield, low in cost and suitable for industrial production.
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Paragraph 0052-0054; 0057; 0058; 006; 0062; 0065; 0066
(2018/10/19)
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- Reactions of Secondary Amines with Dichlorocarbene Generated in Aqueous–Alkaline Medium in the Presence of N-Methylmorpholine N-Oxide
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Dichlorocarbene generated from chloroform in aqueous–alkaline medium in the presence of N-methylmorpholine N-oxide is converted to phosgene which reacts in situ with secondary amines to afford tetrasubstituted ureas.
- Hasratyan,Bagdasaryan,Hayotsyan,Attaryan
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p. 959 - 960
(2018/07/31)
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- Metal-free direct thiocarbamation of imidazopyridines with carbamoyl chloride and elemental sulfur
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The combination of elemental sulfur and carbamoyl chloride was found to act as a carbamothioyl group surrogate for direct thiocarbamation of imidazopyridines in the absence of a metal catalyst.
- Deng, Jian-Chao,Zhuang, Shi-Bin,Liu, Quan-Zhu,Lin, Zi-Wei,Su, Yu-Liang,Chen, Jia-Hao,Tang, Ri-Yuan
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p. 54013 - 54016
(2017/12/06)
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- Highly efficient one-pot assembly of peptides by double chemoselective coupling
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This study describes a methodological advancement in solution-phase peptide synthesis via the development of a convenient and operational protocol to synthesize oligopeptides in a one-pot three-step cascade method, in which two peptide bonds are introduced chemoselectively. Tri- to hexapeptides were obtained in high global yields (80-95%) with virtually no epimerization as determined via HPLC. The methodology described herein represents a faster, easier and milder approach to the synthesis of peptides, and it operates at equimolar amounts. This protocol comprises the formation of secondary and tertiary amides and is compatible with Z, Boc and Fmoc N-protecting groups as well as the use of d/l and non-proteinogenic amino acids.
- Sampaio-Dias, Ivo E.,Sousa, Carlos A. D.,Silva-Reis, Sara C.,Ribeiro, Sara,García-Mera, Xerardo,Rodríguez-Borges, José E.
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supporting information
p. 7533 - 7542
(2017/09/27)
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- The nonenzymatic decomposition of guanidines and amidines
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To establish the rates and mechanisms of decomposition of guanidine and amidine derivatives in aqueous solution and the rate enhancements produced by the corresponding enzymes, we examined their rates of reaction at elevated temperatures and used the Arrhenius equation to extrapolate the results to room temperature. The similar reactivities of methylguanidine and 1,1,3,3-tetramethylguanidine and their negative entropies of activation imply that their decomposition proceeds by hydrolysis rather than elimination. The influence of changing pH on the rate of decomposition is consistent with attack by hydroxide ion on the methylguanidinium ion (k2 = 5 × 10 -6 M-1 s-1 at 25 C) or with the kinetically equivalent attack by water on uncharged methylguanidine. At 25 C and pH 7, N-methylguanidine is several orders of magnitude more stable than acetamidine, urea, or acetamide. Under the same conditions, the enzymes arginase and agmatinase accelerate substrate hydrolysis 4 × 1014-fold and 6 × 1012-fold, respectively, by mechanisms that appear to involve metal-mediated water attack. Arginine deiminase accelerates substrate hydrolysis 6 × 1012-fold by a mechanism that (in contrast to the mechanisms employed by arginase and agmatinase) is believed to involve attack by an active-site cysteine residue.
- Lewis, Charles A.,Wolfenden, Richard
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supporting information
p. 130 - 136
(2014/01/23)
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- Dialkylcyanamides are more reactive substrates toward metal-mediated nucleophilic addition than alkylcyanides
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The dialkylcyanamide complexes Q[PtCl3(NCNR2)] (Q = Ph3PCH2Ph, R2 = Me21, Et 22, C5H103, C4H8O 4; Q = NMe4, R2 = Me25; Q = NEt4, R 2 = Me26) were synthesized either by dissolving Q 2[Pt2(μ-Cl)2Cl4] in neat NCNR2 (1-4) or by substitution of a NCNR2 ligand with Cl- in [PtCl2(NCNR2)2] by its treatment with QCl (5, 6). Nucleophilic addition of dibenzylhydroxylamine, HON(CH2Ph)2, to 1-6 results in the formation of the complexes Q[PtCl3{NHC(NR2)ON(CH2Ph) 2}] (Q = Ph3PCH2Ph, R2 = Me 2, 7; Et2, 8; C5H10, 9; C 4H8O, 10; Q = Me4N, R2 = Me 211; Q = Et4N, R2 = Me2, 12) that further convert at room temperature in the solid state (1-24 h) or in a solution (0.5-2 h) to the imine complexes Q[PtCl3{N(CH2Ph)C(H)Ph}] (Q = Ph3PCH2Ph, 13; Me4N, 14; Et4N, 15) and the corresponding dialkylureas H2NC(O)NR2. The competitive reactivity study of the nucleophilic addition of HON(CH 2Ph)2 to (Ph3PCH2Ph)[PtCl 3(NCR′)] (R′ = Ph, NR2, CH2Ph) indicated that the reactivity of the coordinated NCNR2 is comparable to NCPh, while NCCH2Ph appeared to be much less reactive than the former two ligands. Compounds 1-6 and 13 were fully characterized by elemental analyses (C, H, N), high resolution ESI-MS, IR, and 1H and 13C{1H} NMR spectroscopy. The structure of 1 was additionally verified by a single-crystal X-ray diffraction.
- Anisimova, Tatyana B.,Bokach, Nadezhda A.,Dolgushin, Fedor M.,Kukushkin, Vadim Yu.
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p. 12460 - 12467
(2013/09/02)
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- Orthoamides and iminium salts LXXIV [1]. Reactions of N,N,N',N'- Tetramethyl-chloroformamidiniumChloride with metals
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N,N,N',N'-Tetramethyl-formamidinium chloride (2a) reacts with elemental sodium in various solvents to give N,N,N',N',N'',N''-hexamethyl-guanidinium chloride (4a). The reaction of 2a with potassium affords N,N,N',N',N'',N'',N''', N'''-octamethyl-oxamidinium dichloride (3a). From the reaction of 2a with magnesium in different solvents in general result mixtures of the salts 4a, 3a and N,N,N',N'-tetramethyl-formamidinium chloride (10a). The composition of these mixtures depends on the solvent and the reaction temperature. Similar results are obtained, when a zinc'copper couple is used instead of magnesium. Very likely from 2a and magnesium or zinc, respectively, organometallic intermediates 11, 12 are formed which could be trapped by aromatic aldehydes and phenylisocyanate. The salt 2a can be reductively coupled by a low-valent titanium reagent to give the oxamidinium salt 3a.
- Kantlehner, Willi,Aichholz, Reiner,Karl, Martin
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body text
p. 305 - 319
(2012/07/13)
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- Coordination chemistry of gold catalysts in solution: A detailed NMR study
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Coordination chemistry of gold catalysts bearing eight different ligands [L=PPh3, JohnPhos (L2), Xphos (L3), DTBP, IMes, IPr, dppf, S-tolBINAP (L8)] has been studied by NMR spectroscopy in solution at room temperature. Cationic or neutral mononuclear complexes LAuX (L=L2, L3, IMes, IPr; X=charged or neutral ligand) underwent simple ligand exchange without giving any higher coordinate complexes. For L2AuX the following ligand strength series was determined: MeOHahex-3-yne -aMe 2S3CO2 -≈DMAP3-≈Cl -. Some heteroligand complexes DTBPAuX exist in solution in equilibrium with the corresponding symmetrical species. Binuclear complexes dppf(AuOTf)2 and S-tolBINAP(AuOTf)2 showed different behavior in exchange reactions with ligands depending on the ligand strength. Thus, PPh3 causes abstraction of one gold atom to give mononuclear complexes LLAuPPh3+ and (Ph3P) nAu+, but other N and S ligands give ordinary dicationic species LL(AuNu)22+. In reactions with different bases, LAu+ provided new oxonium ions whose chemistry was also studied: (DTBPAu)3O+, (L2Au)2OH+, (L2Au) 3O+, (L3Au)2OH+, and (IMesAu) 2OH+. Ultimately, formation of gold hydroxide LAuOH (L=L2, L3, IMes) was studied. Ligand- or base-assisted interconversions between (L2Au)2OH+, (L2Au)3O+, and L2AuOH are described. Reactions of dppf(AuOTf)2 and S-tolBINAP(AuOTf) 2 with bases provided more interesting oxonium ions, whose molecular composition was found to be [dppf(Au)2]3O2 2+, L8(Au)2OH+, and [L8(Au)2] 3O22+, but their exact structure was not established. Several reactions between different oxonium species were conducted to observe mixed heteroligand oxonium species. Reaction of L2AuNCMe+ with S2- was studied; several new complexes with sulfide are described. For many reversible reactions the corresponding equilibrium constants were determined. Copyright
- Zhdanko, Alexander,Stroebele, Markus,Maier, Martin E.
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p. 14732 - 14744
(2013/01/15)
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- Pentaalkylmethylguanidinium methylcarbonates - Versatile precursors for the preparation of halide-free and metal-free guanidinium-based ILs
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Pentaalkylmethylguanidinium methylcarbonates 6 can easily be prepared from pentaalkylguanidines 5 and dimethyl carbonate (DMC) in a sustainable solvent-free synthesis. Most of the title compounds are room temperature ionic liquids (RTILs) which provide convenient access to halide-free guanidinium-based ILs (GILs) 7via acid-base reactions and subsequent decarboxylation, similar to industrially important imidazolium methylcarbonates 1. The Royal Society of Chemistry.
- Oelkers, Benjamin,Sundermeyer, Joerg
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p. 608 - 618
(2011/05/11)
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- A novel family of onium salts based upon isonitroso meldrum's acid proves useful as peptide coupling reagents
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A new family of uronium salts (HTMU, HMMU, and HDmPyMU) based on isonitroso Meldrum's acid (HONM) are reported as stand-alone coupling reagents. Amide bond formation with the use of these reagents occurred more quickly than that with other uronium salts as a result of the presence of a neighboring group effect with a cyclic structure. Thus, these novel onium salts were often more effective in the acylation of poor nucleophiles and in the control of optical purity than related Oxyma- and benzotriazole-based reagents. Among the HONM derivatives, HMMU showed the best performance in reducing racemization and assembling demanding sequences such as the Aib-ACP decapeptide or analogues of Leu-enkephalin pentapeptide, Furthermore, the scope and limitations of the use of HONM as an additive in combination with carbodiimides is discussed.
- El-Faham, Ayman,Subiros-Funosas, Ramon,Albericio, Fernando
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experimental part
p. 3641 - 3649
(2010/09/03)
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- Novel betaines of the hexaalkylguanidinio-carboxylate type
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Betaines 7a, b and 8a, b have been prepared from 3- and 4-piperidinecarboxylic acid and N,N,N′N′-tetraalkyl- chloroformamidinium chlorides via the corresponding methyl esters. These betaines are highly hygroscopic, thermally very stable, and, with the exception of 7b, have rather low melting points. They undergo a surprisingly facile alkaline cleavage of the hexaalkylguanidinium moiety. They react with dichloromethane by a twofold nucleophilic substitution to form methylene dicarboxylates such as 11. The NMR (1H, 13C) data of betaines 7 and 8 are discussed.
- Walter, Matthias,Maas, Gerhard
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experimental part
p. 1617 - 1624
(2010/06/22)
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- Preparation of mixed carbamic/dithiocarbamic anhydrides via silyl carbamates or silyl dithiocarbamates
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The reactions of silyl carbamates and silyl dithiocarbamates with different acid chlorides (carbamoyl/thiocarbamoyl chloride, chloroformates, etc.) have been studied. The obtained mixed anhydrides have different thermal stability. Copyright Taylor & Francis Group, LLC.
- Kardon, Ferenc,Moertl, Maria,Magyarfalvi, Gabor
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p. 192 - 199
(2008/03/17)
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- Preparation of tricyclic imidazopyridines by asymmetric ketone hydrogenation in the presence of RuCl2[(S)-Xyl-P-Phos][(S)-DAIPEN]
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The novel complex RuCl2[(S)-Xyl-P-Phos][(S)-DAIPEN] was identified as a highly active catalyst for the asymmetric reduction of a variety of prochiral ketones possessing an imidazo[1,2-a]pyridine scaffold. The corresponding alcohols were obtained in excellent enantiomeric purities (>96% ee) and served as valuable intermediates for the synthesis of pharmacologically active 7H-8,9-dihydropyrano[2,3-c]imidazo[1,2-a]pyridines. The complexity of these multi-functional substrates required the development of specific reaction conditions. Whereas the reduction with RuCl2[PP][NN] catalysts (Noyori catalysts) has never been reported to occur under aqueous conditions, in the present case, the use of aqueous isopropanol or tert-butanol was not only tolerated, but also turned out to be beneficial, especially when the reduction was conducted at high substrate to catalyst (S/C) ratios.
- Palmer, Andreas Marc,Zanotti-Gerosa, Antonio,Nedden, Hans
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p. 1310 - 1327
(2008/12/20)
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- PROCESS FOR THE PRODUCTION OF INTERMEDIATES FOR THE PREPARATION OF TRICYCLIC IMIDAZOPYRIDINES
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The invention relates to a process for the synthesis of compounds of the formula (1-a) and compounds of the formula (1-b). The compounds of the formula 1-a and the compounds of the formula 1-b, in which the substituents R1, R2, R3, and Arom have the meanings indicated in the description, are valuable intermediates for the preparation of pharmaceutically active compounds.
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Page/Page column 67
(2010/11/29)
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- Copper-catalyzed oxidative desulfurization-oxygenation of thiocarbonyl compounds using molecular oxygen: An efficient method for the preparation of oxygen isotopically labeled carbonyl compounds
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A novel copper-catalyzed oxidative desulfurization reaction of thiocarbonyl compounds, using molecular oxygen as an oxidant and leading to formation of carbonyl compounds, has been developed, and the utility of the process is demonstrated by its application to the preparation of a carbonyl-18O labeled sialic acid derivative. The Royal Society of Chemistry.
- Shibahara, Fumitoshi,Suenami, Aiko,Yoshida, Atsunori,Murai, Toshiaki
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p. 2354 - 2356
(2008/02/09)
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- N-(1-(2,3-DIHYDRO-1H-INDEN-5YL) -2-OXO-3-PYRROLIDINYL) -SULFONAMIDE DERIVATIVES FOR USE AS FACTOR XA INHIBITORS
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The invention relates to at least one chemical entity chosen from compounds of formula (I): wherein: R1 represents a group selected from (II): each ring of which optionally contains a further heteroatom N, Z represents an optional substituent halogen, alk represents alkylene or alkenylene, T represents S, O or NH; R2 represents hydrogen, -C1-6alkyl, - C1-3alkyl CONRaRb, - C1-3alkyl CO2 C1-4alkyl, -CO2 C1-4alkyl or - C1-3alkyl CO2H; Ra and Rb independently represent hydrogen, - C1-6alkyl, or together with the N atom to which they are bonded form a 5-, 6- or 7- membered non-aromatic heterocyclic ring optionally containing an additional heteroatom selected from O, N and S, optionally substituted by C1-4alkyl, and optionally the S heteroatom is substituted by O, i.e. represents S(O)n; n represents 0-2; X represents an optional substituent on the indane ring selected from: halogen, - C1-4alkyl, -C2-4alkenyl and -CF3; Y represents a group -(CH2)mNRcRd substituted on the non-aromatic portion of the indane ring; Rc and Rd independently represent hydrogen, - C1-6alkyl, - C1-4alkylOH, or together with the N atom to which they are bonded form a 4-, 5-, 6- or 7- membered non-aromatic heterocyclic ring, the 5-, 6- or 7- membered non-aromatic heterocyclic ring optionally containing an additional heteroatom selected from O, N or S, and the 4-, 5-, 6- or 7- membered non-aromatic heterocyclic ring optionally substituted by C1-4alkyl or halogen; m represents 0-2; and pharmaceutically acceptable derivative(s) thereof. The invention also relates to processes for the preparation of compound(s) of formula (I), pharmaceutical compositions containing compound(s) of formula (I) and to the use of compound(s) of formula (I) in medicine, particularly in the amelioration of a clinical condition for which a Factor Xa inhibitor is indicated.
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Page/Page column 28-29
(2010/10/20)
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- Synthesis of 4-[5-substituted or unsubstituted phenyl)-3-substituted-1H-pyrazol-1-yl]benzenesulfonamides
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This invention encompasses a novel process for synthesizing the compound represented by formula I: These compounds are useful as non-steroidal anti-inflammatory agents.
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- Synthesis and properties of novel dialkylaminocarbenium salts
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Novel dialkylaminocarbenium salts with metallocomplex counter ions were prepared by the reaction of phosgene with either DMF or tetramethylurea in the presence of metal chlorides. Reactions of organosilicon amides with phosgene gave corresponding carbenium salts, while organosilicon ureas yielded aminoiminocarbenium salts. Dialkylaminochlorocarbenium salts were reduced with hydrosilanes to give dialkylaminocarbenium salts and can be easily hydrolyzed to afford either amides or ureas. Pathways of the reaction with water and alcohols depend on the nature of reagent and the reaction conditions.
- Sheludyakov,Belyakova,Shevchenko,Chernyshev
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p. 997 - 1002
(2007/10/03)
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- Discovery of an orally active series of isoxazoline glycoprotein IIb/IIIa antagonists
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Using isoxazoline XR299 (la) as a starting point for the design of highly potent, long-duration GPIIb/IIIa antagonists, the effect of placing lipophilic substituents at positions α and β to the carboxylate moiety was evaluated. Of the compounds studied, it was found that the n-butyl carbamate 24u1,2 exhibited superior potency and duration of ex vivo antiplatelet effects in dogs. Replacement of the benzamidin-4-yl moiety with alternative basic groups, elimination of the isoxazoline stereocenter, and reversal of the orientation of the isoxazoline ring resulted in lowered potency and/or duration of action.
- Xue, Chu-Biao,Wityak, John,Sielecki, Thais M.,Pinto, Donald J.,Batt, Douglas G.,Cain, Gary A.,Sworin, Michael,Rockwell, Arlene L.,Roderick, John J.,Wang, Shuaige,Orwat, Michael J.,Frietze, William E.,Bostrom, Lori L.,Liu, Jie,Higley, C. Anne,Rankin, F. Wayne,Tobin, A. Ewa,Emmett, George,Lalka, George K.,Sze, Jean Y.,Di Meo, Susan V.,Mousa, Shaker A.,Thoolen, Martin J.,Racanelli, Adrienne L.,Hausner, Elizabeth A.,Reilly, Thomas M.,DeGrado, William F.,Wexler, Ruth R.,Olson, Richard E.
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p. 2064 - 2084
(2007/10/03)
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- Carbonylation of Amines by Carbon Dioxide in the Presence of an Organoantimony Catalyst
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1,3-Dialkylureas (RNHCONHR; where R = Bu, i-Bu, s-Bu, t-Bu, allyl, Ph) and tetramethylurea were successfully prepared at 80 deg C under an initial CO2 pressure of 4.9 MPa, from the corresponding amines and carbon dioxide with catalysis by triphenylstibine oxide and assistance from tetraphosphorus decasulfide (Ph3SbO/P4S10).Monitoring of the reaction by 13C NMR revealed that the successive thiolation of carbamic acid to an intermediate antimony carbamate species and aminolysis of the carbamothioic acid thus formed constitute the reaction course.Cyclic ureas can also be synthesized by similar carbonylations of diamines (RNHCH2CH2NHR'; where R, R' = H, H; Me, H; Ph, H; HOCH2CH2, H; HOCHMeCH2, H; Me, Me).Furthermore, the Ph3SbO/P4S10 catalyst system enabled the preparation of trisubstituted ureas such as 1-butyl-3,3-diethylurea by a selective cocarbonylation of butylamine and diethylamine.
- Nomura, Ryoki,Hasegawa, Yasuhiro,Ishimoto, Mikio,Toyosaki, Takayuki,Matsuda, Haruo
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p. 7339 - 7342
(2007/10/02)
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- Manganese dioxide in a new role of Sulfur extrusion in thioamides
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A simple and efficient procedure for the mild conversion of thioamides to amides in good yields using active manganese dioxide is described.
- Radha Rani,Rahman,Bhalerao
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p. 1953 - 1958
(2007/10/02)
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- Aminosilylation of heterocumulenes and the intramolecular decomposition of their silyl-functionalized adducts
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Heteroorganic amidosilanes are readily obtained by interaction of CO2, CS2 and other heterocumulenes with pentacoordinated diaminosilanes.A comparison is made with the corresponding reactions of tetracoordinated species.Decompositon of these bifunctional organosilanes gives 2-substituted ureido derivatives and base-stabilized low coordinated silicon species, seemingly by a unimolecular thermal β-elimination.
- Corriu, R. J. P.,Lanneau, Gerard F.,Mehta, V. D.
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- Oxidative coupling of amines and carbon monoxide catalyzed by palladium complexes. Mono- and double carbonylation reactions promoted by iodine compounds.
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Iodine is an effective promoter for the carbonylation of primary and secondary amines to ureas using palladium acetate as the catalyst and a base (e.g.K2CO3) in acetonitrile (3 h at 95 deg C and 2.7 atm).Oxamides are formed in excellent yields when secondary amines are carbonylated in the presence of iodide ion and oxygen, while primary amines give ureas as the principal product at 95 deg C, and oxamide at room temperature.
- Pri-Bar, Ilan,Alper, Howard
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p. 1544 - 1547
(2007/10/02)
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- Ortho Amides, XLVI. - Contributions to the Chemistry of Bis(dialkylamino)malononitriles
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The reaction of chloroformamidinium chlorides 2 with sodium cyanide in the two-phase system ether/water affords bis(dialkylamino)malononitriles 3 with good yields.From 3a and morpholine or aniline the guanidines 5 and 6 can be obtained, respectively.Alcohol-free sodium ethoxide transforms 3a into the urea acetal 10b, whereas in the reaction of 3a with alkoxides in alcohol ortho carbamic esters 11a, b are produced.The malonic esters and acetoacetic esters 12 react with 3a in the presence of two equivalents of sodium hydride to give the ketene aminals 13.The reactionof 3a with malononitrile furnishes the guanidinium salt 14, which cyclized by hydrogen chloride to the pyridinetricarbonitrile 15.In the presence of sodium hydride, 3a and malononitrile or cyanoacetic esters 17 from the ketene aminal 16 and the 1,2,3-tricyanopropenides 18a-c, respectively.The analogous salts 20 and 21 result from the reaction of 3a with the barbituric acid derivatives 19a, and b, respectively.Hydrogen chloride reacts in ether with 3a to afford the piperazinetetracarbonitrile 22.Reaction of carboxylic acid chlorides yields the cyanoformamidinium salt 28a; byproducts are acyl cyanides 29 and dimeric acyl cyanides 30.Triethyloxonium tetrafluoroborate transforms 3a into the salt 28b.Bromine and iodine react with 3a to produce the salts 28c, d and 28e, f, respectively, depending on the stoichiometric ratios of the starting materials.The thiocyanate 28g is prepared from sulfur and 3a.
- Kantlehner, Willi,Greiner, Ulrich
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p. 965 - 973
(2007/10/02)
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- AN EXCEPTIONALLY MILD, PHASE TRANSFER CATALYZED METHOD FOR THE CONVERSION OF THIOCARBONYL COMPOUNDS TO CARBONYLS
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The thiocarbonyl group of thioketones, dithioesters, thioamides, and thioureas can be converted to the carbonyl function by treatment with sodium hydroxide under phase transfer conditions.
- Alper, Howard,Kwiatkowska, Caroline,Petrignani, Jean-Francois,Sibtain, Fazle
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p. 5449 - 5450
(2007/10/02)
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- Polymer-Supported Diaryl Selenoxide and Telluroxide as Mild and Selective Oxidizing Agents
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Polystyrene-bound diaryl selenoxide and telluroxide have been prepared, which behaved as mild oxidizing agents for thiols to disulfide, phosphines to phosphine oxides, hydroquinone and catechol to p- and o-benzoquinones, and thioketones to oxo compounds.The telluroxide completed these reactions in shorter periods or under milder conditions than the selenoxide.In addition, they effected novel solvent-dependent reactions of thioamides involving thioureas to 1,2,4-thiadiazoles or to nitriles.In nonacidic solvents, the dehydrosulfurization to nitriles occured in preference to the oxidative dimerization to 1,2,4-thiadiazoles, but an acidic solvent such as acetic acid promoted the latter reaction.
- Hu, Nan Xing,Aso, Yoshio,Otsubo, Tetsuo,Ogura, Fumio
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p. 879 - 884
(2007/10/02)
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- Reactivite du nitrile de sodium I. Action sur les sels d'iminium
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1H and natural abundace 15N NMR spectroscopy has been used to investigate the effect of pH on the reaction of sodium nitrite with iminium salts: three competitive pathways have been detected.In acidic medium, the first step is the hydrolysis of the iminium salts giving amide and amine; the latter reacts with sodium nitrite and nitrosamine is obtained.In basic conditions, the amine is stable and the nucleophilic attack of nitrite ion competes with the two possible hydrolysis reactions.In a non-aqueous medium, simultaneous detection of nitrosamine, amide and methyl nitrite is consistent with an intermediate such as an α amino nitrite ester which may decompose along two different pathways.
- Gouesnard, Jean-Paul,Dorie, Jean
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p. 132 - 136
(2007/10/02)
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- PRODUCTION OF TETRASUBSTITUTED UREAS IN THE RADICAL REACTIONS OF BIS(DIALKYLAMINO)METHOXYMETHANE AND 2-DIMETHYLAMINO-3-ALKYL-1,3-OXAZOLIDINES
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The free-radical transformations of the linear and cyclic analogs of orthoformates containing two nitrogen atoms were studied.Tetramethylurea is formed from bis(dimethylamino)methoxymethane, and N-butyl- and N-phenyl-N-ethyl-N',N'-dimethylureas are formed from 2-dimethylamino-3-butyl- and 2-dimethylamino-3-phenyl-1,3-oxazolidines respectively.
- Kurbanov, D.,Pastushenko, E. V.,Zlot-skii, S. S.,Rakhmankulov, D. L:
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p. 817 - 820
(2007/10/02)
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- Investigations on Diazo Compounds and Azides, 58. Dication Ethers, 5. Formamidinium-substituted Diazaphosphoryl Compounds: Synthesis, Properties, and Reactions Leading to Tetrazoles
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Electrophilic diazoalkane substitution of diazaphosphoryl compounds 4a-c by bis(formamidinium)ethers 3a, b leads to formamidinium-substitited (diazomethyl)phosphoryl compounds 5.These can also be considered as alkenediazonium salts, but the contribution from this resonance structure is low according to 1H NMR and IR data.Reaction of 5a-c with another equivalent of 4a-c under slightly modified conditions yields 2-vinyl-2H-tetrazoles 6 and 7.The identity of the tetrazoles has been confirmed by X-ray structure analysis of 6c as well as by thermolysis of 6c leading to pyrazole 12 which then was hydrolyzed to give the NH-pyrazole 13.
- Maas, Gerhard,Guembel, Helmut,Weise, Gisela,Regitz, Manfred
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p. 2105 - 2117
(2007/10/02)
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- MILD AND SELECTIVE OXIDATIONS WITH POLYSTYRENE-BOUND DIARYL SELENOXIDE
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Polystyrene-bound diaryl selenoxide is sohwn to behave as a mild oxidizing agent for thiol to disulfide, sulfide to sulfoxide, phosphine to phosphine oxide, and hydroquinone to benzoquinone.In addition, it effects solvent-dependent reactions of thioamide to nitrile in usual solvent and to thiadiazole in acetic acid.
- Hu, Nan Xing,Aso, Yoshio,Otsubo, Tetsuo,Ogura, Fumio
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p. 603 - 606
(2007/10/02)
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- PUSH-PULL OLEFINS FROM BIS(FORMAMIDINIUM) ETHERS
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Bis(N,N,N',N'-tetraalkyl)formamidinium ethers, readily prepared from a N,N,N',N'-tetraalkyl urea and triflic anhydride, yield push-pull olefins with activated methylene compounds H2CXY, where X, Y are CN, COOR, C6H4-4-NO2.
- Maas, Gerhard,Feith, Bernhard
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p. 1073 - 1080
(2007/10/02)
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- N-Nitroso- and N-Nitrotrialkylureas and Their Decomposition
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The synthesis and decomposition of N-(n-butyl)-N',N'-dimethyl-N-nitrosourea (2a), N-(n-butyl)-N',N'-dimethyl-N-nitrourea (3a), N',N'-dimethyl N-(1-norbornyl)-N-nitrosourea (2b), N',N'-dimethyl-N-(1-norbornyl)-N-nitrourea (3b) are described.Several of the compounds show complex NMR spectra ascribable to rotational isomerism.Decomposition of 2a and 3a gave n-butyl N,N-dimethylcarbamate and tetramethylurea, while decompostion of 2b and 3b in methylene chloride gave 1-norbornyl N,N-dimethylcarbamate and 1-norbornyl chloride.These products are formed via diazotic acid derivatives and carbonium ion pairs; the reaction mechanism is essentially the same as that established for the closely related N-nitrosoamides.In concentrated solutions, nitrosourea 2a yielded a new product, amino acid 20.
- White, Emil H.,Ryan, Thomas J.,Hahn, Bo Sup,Erickson, Ronald H.
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p. 4860 - 4866
(2007/10/02)
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- N-NITROSAMINES AS REAGENTS FOR THE =C=S=C=O TRANSFORMATION
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N-nitrosopiperidine and N-nitroso-N-methylaniline react in acidic solution with thiocarbonyl compounds to give the corresponding carbonyl analogues.Secondary- and tertiary thioamides, xanthione, thio- and dithiobutyrolactone, thiocoumarin, certain thiourea derivatives, dithio-O,O-thiocarbonic, S,S-trithiocarbonic- and N,N disubstituted thiocarbamic esters are all converted into the corresponding O-analogues.Thiobenzamide and N-phenylthiourea yield 1,2,4-thiadiazoles.All the reactions are run with iodide (I-) as NO+-carrier.The kinetics of the reaction have been studied under pseudo-first order conditions, and the reaction rate is proportional to the Pearson's nucleophilicity parameter of ions.The =C=S =C=O transformation is also found to take place in gastric juice.
- Jorgensen, K. A.,El-Wassimy, M. T. M.,Lawesson, S. -O.
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p. 469 - 474
(2007/10/02)
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- THE =C=S -> =C=O TRANSFORMATION USING THE SOFT NO(+)-SPECIES
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The reaction of NaNO2 in acidic solution with thiocarbonyl compounds has been studied.Secondary- and tertiary thioamides, 1-benzyl-hexahydro-2H-azepine-2-thione, 5-ethyl-5-phenyl thiobarbituric acid, certain thiourea derivatives, 2H-1-benzopyran-2-thione, O,O-diphenyl-thiocarbonic ester, O,S-diphenyl-dithiocarbonic ester, N,N-dimethyl-S-phenyl-dithiocarbamatic ester, N-ethyl-N-phenyl-O-ethyl-thiocarbamatic ester are all converted into the corresponding carbonyl-analogues. 4,4'-Bis(dimethylamino)-thiobenzophenone (Michler's thioketone) gives 3-nitro-4,4'-bis(dimethylamino)-benzophenone at room temperature.At (-10 deg C)-(-5 deg C) the expected oxo compound is obtained as the main product together with 4-(N-nitroso-methylamino)-4'-(dimethylamino)-benzophenone.
- Joergensen, K. A.,Ghattas, A.-B.A.G.,Lawesson, S.-O.
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p. 1163 - 1168
(2007/10/02)
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- Orthoamides, XXXV. - Preparation of O,N-Functional Trisubstituted Acetonitriles
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Trichloroacetonitrile (7) reacts with molar amounts of alcoholates in alcohols to give mixtures of orthocarbonates 10 and trichloroacetimidates 9.The action of 7 on 3 moles of sodium ethoxide in heptane affords triethoxyacetonitrile 3b among other products, such as 9b, 10b and the imidate 12.The nitrile 3a can be obtained from 7 and sodium methoxide in ether in moderate yields. - The orthocarbonic acid derivatives 10b, 20a and 21a are transformed by acyl cyanides into the nitriles 3b, 4a, and 5a, respectively.N,N,N',N',N'',N''-hexamethylguanidinium cyanide (23a) is f ormed in the reaction of 22 with acetyl cyanide. - The salts 30a-32a react with alkali cyanides to form the nitriles 3b, 4a, and 5a, respectively.The nitrile 2a transfers cyanide ions to the carbenium ions 30a and 31a to yield the nitriles 3b and 4a, respectively.
- Kantlehner, Willi,Maier, Thomas,Kapassakalidis, Joannis J.
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- Process for the manufacture of perfluoro-alkoxy-propionic acid fluorides
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Perfluoro-alkoxy propionic acid fluorides may be obtained by reacting hexafluoro-propene epoxide with a perfluoro-carboxylic fluoride in an aprotic polar solvent in the presence of a N,N,N', N'-tetrasubstituted diaminodifluoromethane as catalyst. The compounds obtained may be used as starting products for valuable perfluoro ethers which are highly inert towards heat or aggressive chemicals, such as fluorine.
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