- [Co(MeTAA)] Metalloradical Catalytic Route to Ketenes via Carbonylation of Carbene Radicals
-
An efficient synthetic strategy towards beta-lactams, amides, and esters involving “in situ” generation of ketenes and subsequent trapping with nucleophiles is presented. Carbonylation of carbene radical intermediates using the cheap and highly active cobalt(II) tetramethyltetraaza[14]annulene catalyst [Co(MeTAA)] provides a convenient one-pot synthetic protocol towards substituted ketenes. N-tosylhydrazones are used as carbene precursors, thereby bridging the gap between aldehydes and ketenes. Activation of these carbene precursors by the metalloradical cobalt(II) catalyst affords CoIII-carbene radicals, which subsequently react with carbon monoxide to form ketenes. In the presence of a nucleophile (imine, alcohol, or amine) in the reaction medium the ketene is immediately trapped, resulting in the desired products in a one-pot synthetic protocol. The β-lactams formed upon reaction with imines are produced in a highly trans-selective manner.
- Chirila, Andrei,van Vliet, Kaj M.,Paul, Nanda D.,de Bruin, Bas
-
p. 2251 - 2258
(2018/04/09)
-
- Reactivity of Me-pma RhI and IrI Complexes upon Deprotonation and Their Application in Catalytic Carbene Carbonylation Reactions
-
Dehydrogenative oxidation of amines is a relevant process in metal-mediated catalysis, with the amines being either substrates or ligands. Transformation of amine- into imine-type ligands in the coordination sphere of a transition metal can be an important catalyst activation process. The behaviour of secondary pyridin-2-ylmethanamine (pma) ligands in the corresponding rhodium and iridium complexes upon NH deprotonation varies, depending on a number of factors. In this paper the behaviour of the Me-pma ligand [Me-pma = N-methyl-1-(pyridin-2-yl)methanamine] bound to [Rh(cod)]+ and [Ir(cod)]+ was studied. Whereas the iridium amido complex could be obtained upon NH deprotonation, the rhodium complex instantaneously disproportionated into a free pma ligand and an unusual dinuclear complex, adopting a structure with two RhI metal centres hosted by a dianionic (pma-2H)2- ligand, and with the ligand coordinating to Rh2 as an "aza-allyl" fragment. The study gives further proof for the effect of pyridine ligation on the previously observed charge-transfer from the ligand to the metal. Furthermore, the catalytic activity of both the Ir and the Rh species with Me-pma in carbene carbonylation reactions to generate ketenes was studied.
- Tang, Zhou,Tejel, Cristina,Martinez De Sarasa Buchaca, Marc,Lutz, Martin,Van Der Vlugt, Jarl Ivar,De Bruin, Bas
-
p. 963 - 974
(2016/03/15)
-
- Carboxyl activation of 2-mercapto-4,6-dimethylpyrimidine through n-acyl-4,6-dimethylpyrimidine-2-thione: A chemical and spectrophotometric investigation
-
2-Mercapto-4,6-dimethylpyrimidine, as effective carboxyl activating group, has been successfully proved by converting it into respective acyl derivatives and the subsequent conversion to the amides and esters respectively using amines, amino alcohols and alcohols. The aminolysis and esterification were monitored chemically and spectrophotometrically. This paved way to establish that the above mercaptopyrimidine derivative is an efficient carboxyl activating group applicable in solid phase peptide synthesis.
- Rajan
-
p. 287 - 291
(2015/01/30)
-
- Carbene radicals in cobalt(II)-porphyrin-catalysed carbene carbonylation reactions; A catalytic approach to ketenes
-
One-pot radicals: Cobalt(III)-carbene radicals, generated by metallo-radical activation of diazo compounds and N-tosylhydrazone sodium salts with cobalt(II) complexes of porphyrins, readily undergo radical addition to carbon monoxide, allowing the catalytic production of ketenes. These ketenes subsequently react with various amines, alcohols and imines in one-pot tandem transformations to produce differently substituted amides, esters and β-lactams in good isolated yields. Copyright
- Paul, Nanda D.,Chirila, Andrei,Lu, Hongjian,Zhang, X. Peter,Debruin, Bas
-
supporting information
p. 12953 - 12958
(2013/10/01)
-
- Thermodynamics of phenylacetamides synthesis: Linear free energy relationship with the pK of amine
-
The effective equilibrium constants K′C expressed through the total concentrations of the reagents for the synthesis of N-phenylacetyl-derivatives in aqueous medium from phenylacetic acid and various primary amino compounds have been determined with penicillin acylase as a catalyst. Broad specificity of penicillin acylase (EC 3.5.1.11) to amino components made possible to investigate the acylation of primary amines with different structures and physicochemical properties. Analysis of different components of the effective standard Gibbs energy change ΔGC o′ has revealed favorable thermodynamics for the synthesis of phenylacetamides from unionized substrates forms, however the ionization of reactants carboxy and amino groups in aqueous solutions pushes the equilibrium position to the hydrolysis especially in case of highly basic amines. A linear correlation between the standard Gibbs energy change for amide bond formation from the unionized reagents species and the basicity of amino group was observed: ΔGTo=-3.56pKamine+7.71(kJ/mol). The established linear free energy relationship (LFER) allows to predict the thermodynamic parameters for direct condensation of phenylacetic acid with any amine of known pK. Condensation of phenylacetic acid and amines with pK value within 1.5-8.5 was shown to be thermodynamically favorable in homogeneous aqueous solution. .
- Guranda, Dorel T.,Ushakov, Gennadij A.,Yolkin, Petr G.,Svedas, Vytas K.
-
-
- A straightforward synthesis of N-monosubstituted α-keto amides via aerobic benzylic oxidation of amides
-
An efficient sodium bicarbonate promoted aerobic oxidation reaction to prepare N-monosubstituted α-keto amides in the presence of n-tetrabutylammonium hydrogensulfate (TBAHS) was described. This reaction provides a very simple and convenient synthetic route to N-monosubstituted α-keto amides from easily available aryl- or heteroarylacetamides in good to high yields without using toxic reagents and harsh conditions.
- Shao, Jun,Huang, Xiaomei,Wang, Siyuan,Liu, Bingxin,Xu, Bin
-
supporting information; experimental part
p. 573 - 579
(2012/01/13)
-
- An improved method of amide synthesis using acyl chlorides
-
A simple, mild and highly efficient condition for amide synthesis from acyl chlorides has been developed to minimize hydrolysis, racemization and other side reactions. This method should expand capabilities in the peptide coupling area.
- Zhang, Li,Wang, Xiao-jun,Wang, Jing,Grinberg, Nelu,Krishnamurthy, DhileepKumar,Senanayake, Chris H.
-
supporting information; experimental part
p. 2964 - 2966
(2009/08/07)
-
- Nonpeptide inhibitors of measles virus entry
-
Measles virus (MV) is one of the most infectious pathogens known. Despite the existence of a vaccine, over 500 000 deaths/year result from MV or associated complications. Anti-measles compounds could conceivably reverse these statistics. Previously, we described a homology model of the MV fusion protein trimer and a putative binding site near the head-neck region. The resulting model permitted the identification of two nonpeptidic entry inhibitors. Here, we present the design, synthesis, and bioevaluation of several series of fusion inhibitors and describe their structure-activity relationships (SAR). Five simply substituted anilides show low-μM blockade of the MV, one of which (AS-48) exhibits IC50 = 0.6-3.0 μM across a panel of wild-type MV strains found in the field. Molecular field topology analysis (MFTA), a 2D QSAR approach based on local molecular properties (atomic charges, hydrogen-bonding capacity and local lipophilicity), applied to the anilide series suggests structural modifications to improve potency.
- Sun, Aiming,Prussia, Andrew,Zhan, Weiqiang,Murray, Ernest E.,Doyle, Joshua,Cheng, Li-Ting,Yoon, Jeong-Joong,Radchenko, Eugene V.,Palyulin, Vladimir A.,Compans, Richard W.,Liotta, Dennis C.,Plemper, Richard K.,Snyder, James P.
-
p. 5080 - 5092
(2007/10/03)
-
- A mild and efficient procedure for the conversion of aromatic carboxylic esters to secondary amides
-
A mild and efficient procedure has been developed for the conversion of aromatic carboxylic esters to secondary amides using reusable Zn dust with microwave heating in the presence of N,N-dimethylformamide or conventional heating by stirring in an oil bath using THF as solvent. Zn dust can be reused several times after simple washing with dil. HC1 and distilled water.
- Arora, Revika,Paul, Satya,Gupta, Rajive
-
p. 1137 - 1140
(2007/10/03)
-
- Discovery of a novel lead structure for anti-malarials
-
From a library of 61 compounds available from former studies, 2,5-bis-acylaminobenzophenone 1 was identified as a lead structure for a novel class of anti-malaria agents active against multi-resistant Plasmodium falciparum strain Dd2. Some structural modifications of this initial lead demonstrated the potential for further improvement of the anti-plasmodial activity of this novel class of anti-malarials. Copyright
- Wiesner, Jochen,Wi?ner, Pia,Dahse, Hans-Martin,Jomaa, Hassan,Schlitzer, Martin
-
p. 785 - 792
(2007/10/03)
-
- Structure-Activity Studies on Amides Inhibiting Photosystem II
-
A series of N-phenylanilides and N-phenylureas have been synthesised and their 'in vitro' photosystem II activity measured in a cell-free system.An attempt was made to correlate 'in vitro' data with a novel hydrophobicity parameter ?amide (related to the substituent on the phenyl ring) and with the torsion angle θ between the planes of the phenyl and amide moieties.
- Lewis, Richard J.,Camilleri, Patrick,Kirby, Anthony J.,Marby, Craig A.,Slawin, Alexandra A.,Williams, David J.
-
p. 1625 - 1630
(2007/10/02)
-