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Straightforward Synthesis (straightforward + synthesis)
Selected AbstractsStraightforward Synthesis of ,-Substituted Prolines by Cross-MetathesisEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 16 2008Marco Lumini Abstract The synthesis of several ,-substituted N -Boc-protected prolines has been achieved by cross metathesis (CM) of N -Boc-allylproline 5 with terminal long chain alkenes and alkenes bearing hydroxy, silyloxy, ester, and O -acetylglucosamido groups. The CM occurred with good selectivity and short reaction time under microwave heating conditions, affording yields in the range of 40,92,%. Addition of Ti(OiPr)4 as a Lewis acid allowed a slight increase of the yield in the case of alkenes with Lewis basic substituents. The CM was also successfully applied to allylproline protected with trichloroacetaldehyde 4, but the intermediate products were less practical for further deprotection and elaboration. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] A Straightforward Synthesis of Isoxazoline-Based Carbocyclic Nucleosides from 1,3-Cyclohexadiene through Nitrosocarbonyl ChemistryEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 36 2007Paolo Quadrelli Abstract 3-Benzoyl-2-oxa-3-azabicyclo[2.2.2]oct-5-ene undergoes cycloaddition with benzonitrile oxide to afford a mixture of syn and anti regioisomeric cycloadducts. The anti cycloadducts were easily elaborated to stereodefined isoxazoline-based carbocyclic aminols that serve as synthons for the linear construction of purine nucleosides. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] 4- exo - dig Cyclocarbopalladation: A Straightforward Synthesis of Cyclobutanediols from Acyclic ,-Bromopropargylic Diols under Microwave Irradiation Conditions,EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 6 2006Christophe Bour Abstract Treatment of acyclic ,-bromopropargylic diols with tributylstannylated alkynes under palladium catalysis and microwave irradiation conditions gives high yields of the bis(alkylidene)cyclobutanediol derivatives and cyclobutenediols through an efficient 4- exo - dig cyclocarbopalladation. The cyclization is general with a wide variety of alkyne derivatives and gives access to new cyclobutane ring systems bearing one exocyclic double bond and one eneyne substituent as well as bicyclic dienes sharing a common double bond that may be of interest for further elaborations of complex molecules. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] Straightforward Synthesis of Non-Natural Selenium Containing Amino Acid Derivatives and PeptidesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 20 2005Antonio L. Braga Abstract A series of non-natural selenium-containing amino acid derivatives and peptides have been synthesized, in a flexible and modular strategy. The peptide coupling reaction between N -protected amino acids and chiral ,-seleno amines afforded the desired products in high yields. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Straightforward Synthesis of Labeled and Unlabeled Pyrimidine d4Ns via 2,,3, - Diyne seco Analogues through Olefin Metathesis ReactionsEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 4 2003Isabelle Gillaizeau Abstract The synthesis of dideoxynucleosides (ddNs) or didehydro-dideoxynucleosides (d4Ns) from nucleosides has been extensively reviewed. While previously described methods are based on the modification of the 2,- and/or 3,-OH group of the intact ribose moiety, the use of a ring-closing metathesis (RCM) for the formation of the unsaturated cyclic system of nucleosides could be a straightforward approach to the d4Ns. Thus, as part of our drug labeling program, this paper reports a straightforward synthesis of 2,,3,-didehydro-2,,3,-dideoxyuridine (d4U) and [1,,2,,3,,4,,5,- 13C5,6- 13C,1,3- 15N2]d4T using the RCM protocol. This paper discusses the preparation of nucleoside dienes and the activity of ruthenium-based metathesis catalysts. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] A Straightforward Synthesis of N -Functionalized ,-DiiminesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 2 2003Alexandrine Maraval Abstract Reaction of Schwartz's reagent [Cp2ZrHCl]n (1) (one or two equivalents) with gem -dinitrile compounds of the type X(CN)2 [X = CMe2, CBenz2, P(NiPr2)2] gives the corresponding mono- and di- N -zirconated imino complexes selectively. Substitution reactions of the zirconocene metal fragment with electrophiles such as, for example, chlorophosphanes of the type R2PCl, acid chlorides RC(O)Cl or the iminium salt [CH2NMe2]Cl allowed the preparation of a large variety of stable N -functionalized mono- and ,-diimine derivatives. The nature of the X group is of particular importance for the success of the substitution reaction step. The X-ray crystal structures obtained for the N -functionalized gem -aldimino-nitrile compounds 9, 10b, the N -phosphorylated ,-diimine 32, and the gem -formyl nitrile derivative 12b are presented. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] Straightforward Synthesis of Ethers: Metal-Free Reductive Coupling of Tosylhydrazones with Alcohols or Phenols,ANGEWANDTE CHEMIE, Issue 29 2010José Barluenga Prof. Einfach zum Ether: Erhitzen von Lösungen, die ein Tosylhydrazon und ein Phenol oder einen anderen Alkohol enthalten, in Gegenwart von K2CO3 ergibt die entsprechenden Arylalkyl- und Alkylalkylether (siehe Schema; MW=Mikrowellen, Ts=Tosyl). Die Reaktion kommt als neue Methode für die reduktive Veretherung von Carbonylverbindungen in Betracht. [source] ChemInform Abstract: A Straightforward Synthesis of 2-(1-Vinyl-1H-pyrrol-2-yl)-1H-benzimidazoles from 1-Vinyl-1H-pyrrole-2-carbaldehydes and o-Phenylenediamine.CHEMINFORM, Issue 11 2010Boris A. Trofimov Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: A Straightforward Synthesis of Benzothiazines.CHEMINFORM, Issue 24 2009Carolina Gimbert Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: First Straightforward Synthesis of 2,4-Disubstituted Benz[g]isoquinoline-3,5,10(2H)-triones, 1,2,3,5-Substituted Naphtho[3,2,1-de]isoquinoline-4,7-diones, and 6-Substituted Benzo[h]pyrido[3,4,5-kl]-1,2,3,4-tetrahydroacridine-5,8-diones.CHEMINFORM, Issue 50 2008Jan Jacobs Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Intramolecular Pd(II)-Catalyzed Cyclization of Propargylamides: Straightforward Synthesis of 5-Oxazolecarbaldehydes.CHEMINFORM, Issue 42 2008Egle M. Beccalli Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Straightforward Synthesis of CF3 -Substituted Triarylethenes by Stereoselective Threefold Cross-Coupling Reactions.CHEMINFORM, Issue 12 2008Youhei Takeda Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Tributyltin Hydride Mediated Straightforward Synthesis of a New Isoxazolo-benzazulene Ring System.CHEMINFORM, Issue 1 2007Vijay Singh Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Straightforward Synthesis of Depsiphosphonopeptides via Mannich-Type Multicomponent Condensation.CHEMINFORM, Issue 28 2006Jiaxi Xu Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Arynes in a Three-Component Coupling Reaction: Straightforward Synthesis of Benzoannulated Iminofurans.CHEMINFORM, Issue 45 2004Hiroto Yoshida Abstract For Abstract see ChemInform Abstract in Full Text. [source] A Straightforward Synthesis of (E)-,-Alkenyl-,,,-Unsaturated ,-Lactones by a Tandem Ring-Closing/Cross-Coupling Metathesis Process.CHEMINFORM, Issue 5 2004Marie-Alice Virolleaud Abstract For Abstract see ChemInform Abstract in Full Text. [source] ChemInform Abstract: A Straightforward Synthesis of Some Fused Aza-Arenes via Nucleophilic Displacement of a Ring Hydrogen Atom in Nitroarenes by Aromatic Hydrazone Anions.CHEMINFORM, Issue 30 2002Koji Uehata Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: A Straightforward Synthesis of Pyridopyrazino[2,3-b]indoles and Indolo[2,3-b]quinoxaline.CHEMINFORM, Issue 36 2001France-Aimee Alphonse Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Straightforward Synthesis of (R)-(,)-KjellmanianoneCHEMISTRY - A EUROPEAN JOURNAL, Issue 4 2004Jens Christoffers Prof. Dr. Abstract A direct route to enantiomerically pure (,)-kjellmanianone is reported. The synthesis involves a cerium-catalyzed ,-hydroxylation and an enzyme-catalyzed procedure to resolve tertiary alcohols at key stages. The intermediate ,-oxo ester was ,-hydroxylated to give good yields of racemic kjellmanianone. The resolution of the racemic material was achieved by enzymatic saponification, followed by a chemical decarboxylation sequence to give enantiopure (,)-kjellmanianone with 99,% ee. Bromination then afforded the (,)-bromo derivative, whose X-ray structure provided evidence for the R configuration of (,)-kjellmanianone. [source] Synthesis of Enantiopure Sulfonimidamides and Elucidation of Their Absolute Configuration by Comparison of Measured and Calculated CD Spectra and X-Ray Crystal Structure DeterminationCHEMISTRY - A EUROPEAN JOURNAL, Issue 2 2010Christin Worch Abstract Straightforward syntheses of enantiopure N -benzoyl- and N - tert -butyloxycarbonyl-protected sulfonimidamides, which can be used as building blocks in newly designed catalysts, are presented. Key synthetic step is a dynamic resolution of a racemic sulfinic acid sodium salt. All subsequent transformations proceed stereospecifically. The absolute configurations at the sulfur atoms of both sulfonimidamides were determined by comparison of measured and calculated CD spectra. An X-ray crystal structure determination of a sulfonimidoylguanidine derivative confirmed this result. [source] Using Chiral Ligand Substituents To Promote the Formation of Dinuclear, Double-Stranded Iron, Manganese, and Zinc MesocatesEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 33 2007Stuart D. Reid Abstract The synthesis and structures of dinuclear manganese, iron, and zinc complexes of chiral di-iminodipyrromethane ligands (L) are reported. Schiff base condensation reactions between 5,5,-diformyl-2,2,-dipyrromethane and the chiral amines (,)-(R)-CH(Me)tBu and (+)-(R)-CH(Me)Ph result in the straightforward synthesis of the new, chiral ligands H2L2 and H2L3, respectively. Salt elimination reactions between K2L and divalent Mn and Fe halides, and protonolysis reactions between ZnMe2 and H2L result in the formation of the new dinuclear complexes [M2(L)2]. Investigation of the structures of these compounds in solution and in the solid state reveal that chiral mesocates are formed for L = L2, whereas for L = L3, a racemic mixture of helicates is present.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] Synthesis and Biological Evaluation of Pretubulysin and Derivatives,EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 36 2009Angelika Ullrich Abstract Pretubulysin, a biosynthetic precursor of the tubulysins, shows potent biological activity in the subnanomolar range towards various tumor cell lines. Its activity is only slightly less than those of the structurally more complex tubulysins. With a straightforward synthesis to hand, pretubulysin is an ideal lead structure for the development of tubulysin-based anticancer drugs(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] A Practical and Efficient Approach to PNA Monomers Compatible with Fmoc-Mediated Solid-Phase Synthesis Protocols,EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 34 2008Andrea Porcheddu Abstract A straightforward synthesis of orthogonally protected PNA monomers is described. Protected aminoethylglycine (Aeg) monomers were efficiently prepared by reductive amination of N -Fmoc-glycinaldehyde with glycine methyl ester and the subsequent acylation of the free amine with N -bis-Boc-protected nucleobase acetic acids. The exocyclic amine group of the nucleobases, including the notoriously difficult-to-protect guanine nucleobase, was protected with a bis-Boc carbamate group; this increased the solubility of the nucleobases in the most common organic solvents. The current protocol allows all Aeg monomers to be prepared on both the micro- and macroscale, which avoids or minimizes the use of toxic reagents or solvents, and moreover, cheap starting materials are used. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Synthesis of an Optically Active Decahydro-6-isoquinolone Scaffold with a Quaternary StereocenterEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 12 2004Jens Christoffers Abstract A straightforward synthesis of optically active decahydro-6-isoquinolone derivative 3, containing a quaternary stereocenter, is reported. The starting (R)-configured enantiopure enone 2, which is readily accessible through a copper-catalyzed, L -valine amide mediated Michael reaction and a subsequent Robinson annulation, was hydrogenated with Pd/C in iPrOH to give the decahydroisoquinolone 4. Treatment of 4 with ethyleneglycol in the presence of PPTS yielded the dioxolane-protected derivative 7. A sequence of ester reduction with LiAlH4 and subsequent Ley oxidation of the resulting primary alcohol 10 accomplished the synthesis. Enantiomerically pure aldehyde 3, with three groups for further functionalization, was thus obtained in 63% overall yield. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source] Straightforward Synthesis of Labeled and Unlabeled Pyrimidine d4Ns via 2,,3, - Diyne seco Analogues through Olefin Metathesis ReactionsEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 4 2003Isabelle Gillaizeau Abstract The synthesis of dideoxynucleosides (ddNs) or didehydro-dideoxynucleosides (d4Ns) from nucleosides has been extensively reviewed. While previously described methods are based on the modification of the 2,- and/or 3,-OH group of the intact ribose moiety, the use of a ring-closing metathesis (RCM) for the formation of the unsaturated cyclic system of nucleosides could be a straightforward approach to the d4Ns. Thus, as part of our drug labeling program, this paper reports a straightforward synthesis of 2,,3,-didehydro-2,,3,-dideoxyuridine (d4U) and [1,,2,,3,,4,,5,- 13C5,6- 13C,1,3- 15N2]d4T using the RCM protocol. This paper discusses the preparation of nucleoside dienes and the activity of ruthenium-based metathesis catalysts. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] A Novel Synthesis of Highly Substituted Perhydropyrrolizines, Perhydroindolizines, and Pyrrolidines: Inhibition of the Peptidyl-Prolyl cis/trans Isomerase (PPIase) Pin1HELVETICA CHIMICA ACTA, Issue 2 2007Romain Siegrist Abstract In this paper, we describe the synthesis and biological evaluation of highly substituted perhydropyrrolizines that inhibit the peptidyl-prolyl cis/trans isomerase (PPIase) Pin1, an oncogenic target. The enzyme selectively catalyzes the cis/trans isomerization of peptide bonds between a phosphorylated serine or threonine, and proline, thereby inducing a conformational change. Such structural modifications play an important role in many cellular events, such as cell-cycle progression, transcriptional regulation, RNA processing, as well as cell proliferation and differentiation. Based on computer modeling (Fig.,2), the new perhydropyrrolizinone derivatives (,)- 1a,b, decorated with two substituents, were selected and synthesized (Schemes,1,3). While enzymatic assays showed no biological activity, 15N,1H-HSQC-NMR spectroscopy revealed that (,)- 1a,b bind to the WW recognition domain of Pin1, apparently in a mode that does not inhibit PPIase activity. To enforce complexation into the larger active site rather than into the tighter WW domain of Pin1 and to enhance the overall binding affinity, we designed a perhydropyrrolizine scaffold substituted with additional aromatic residues (Fig.,5). A novel, straightforward synthesis towards this class of compounds was developed (Schemes,4 and 5), and the racemic compounds (±)- 22a,22d were found to inhibit Pin1 with Ki values (Ki,=,inhibition constant) in the micromolar range (Table,2). To further enhance the potency of these inhibitors, the optically pure ligands (+)- 22a and (+)- 33b,c were prepared (Schemes,6 and 7) and shown to inhibit Pin1 with Ki values down to the single-digit micromolar range. According to 15N,1H-HSQC-NMR spectroscopy and enzymatic activity assays, binding occurs at both the WW domain and the active site of Pin1. Furthermore, the new synthetic protocol towards perhydropyrrolizines was extended to the preparation of highly substituted perhydroindolizine ((±)- 43; Scheme,8) and pyrrolidine ((±)- 48a,b; Scheme,9) derivatives, illustrating a new, potentially general access to these highly substituted heterocycles. [source] A New Approach to Pyrrolocoumarin Derivatives by Palladium-Catalyzed Reactions: Expedient Construction of Polycyclic Lamellarin ScaffoldADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 11-12 2009Lei Chen Abstract A new and efficient protocol for straightforward synthesis of chromeno[3,4- b]pyrrol-4(3H)-one derivatives by palladium-catalyzed sequential coupling/cyclization reactions has been developed. The key strategy relies on creation of pyrrole ring through palladium-catalyzed intramolecular hydroamination of related acetylenic aminocoumarins. The synthetic utility of the obtained chromeno[3,4- b]pyrrol-4(3H)-one product has been demonstrated by the expedient synthesis of polycyclic lamellarin scaffold in four steps. It provides a new entry to synthesis of potentially valuable lamellarin analogues. [source] Homobimetallic Ruthenium Vinylidene, Allenylidene, and Indenylidene Complexes: Synthesis, Characterization, and Catalytic StudiesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 3 2009Xavier Sauvage Abstract Four homobimetallic ruthenium-(p -cymene) complexes bearing a tricyclohexylphosphine ligand and polyunsaturated carbon-rich fragments were obtained via a vinylidene-allenylidene-indenylidene cascade pathway from the ethylene complex [(p -cymene)Ru(,-Cl)3RuCl(PCy3)(,2 -C2H4)] (7a). All the products were isolated and fully characterized by IR and NMR spectroscopies. The molecular structure of the indenylidene complex 11 was determined by X-ray crystallographic analysis. The catalytic activity of the four complexes was probed in various types of olefin metathesis reactions and compared with those of a related homobimetallic ruthenium-benzylidene complex, as well as first, second, and third generation monometallic Grubbs catalysts. In the ring-closing metathesis (RCM) of diethyl diallylmalonate, the homobimetallic ruthenium-indenylidene complex 11 outperformed all the ruthenium-benzylidene complexes under investigation and was only slightly less efficient than its monometallic parent. Cross-metathesis experiments with ethylene showed that deactivation of ruthenium-benzylidene or indenylidene complexes was due to the rapid bimolecular decomposition of methylidene active species into ethylene complex 7a. Vinylidene and allenylidene complexes were far less efficient catalyst precursors for ring-opening metathesis polymerization (ROMP) or RCM and remained inert under an ethylene atmosphere. Their catalytic activity was, however, substantially enhanced upon addition of an acidic co-catalyst that most likely promoted their in situ transformation into indenylidene species. Due to its straightforward synthesis and high metathetical activity, homobimetallic ruthenium-indenylidene complex 11 is a valuable intermediate for the preparation of the Hoveyda,Grubbs catalyst [Cl2Ru(PCy3)(CH- o -O- i- PrC6H4)] via stoichiometric cross-metathesis with 2-isopropoxystyrene. The procedure did not require any sacrificial phosphine and the transition metal not incorporated into the final product was easily recovered and recycled at the end of the process. [source] An Efficient synthesis of orthogonally protected trans - and cis -4-aminopipecolic acidJOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 5 2006István Szatmári A straightforward synthesis of orthogonally N,/N, -protected trans - and cis -4-aminopipecolic acid is reported, starting from methyl cis -4-hydroxypiperidine-2-carboxylate. The two diastereomers were synthesized with the aid of C-4 inversion (the trans isomer) or double C-4 inversion (the cis isomer). [source] Synthesis of well-defined photoresist materials by SET-LRPJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 10 2010Sven Fleischmann Abstract Single electron transfer-living radical polymerization (SET-LRP) provides an excellent tool for the straightforward synthesis of well-defined macromolecules. Heterogeneous Cu(0)- catalysis is employed to synthesize a novel photoresist material with high control over the molecular architecture. Poly(,-butyrolactone methacrylate)- co -(methyladamantly methacrylate) was synthesized. Kinetic experiments were conducted demonstrating that both monomers, ,-butyrolactone methacrylate (GBLMA) and methyl adamantly methacrylate (MAMA), are successfully homopolymerized. In both cases polymerization kinetic is of first order and the molecular weights increase linearly with conversion. The choice of a proper solvent was decisive for the SET-LRP process and organic solvent mixtures were found to be most suitable. Also, the kinetic of the copolymerization of GBLMA and MAMA was investigated. Following first order kinetics in overall monomer consumption and exhibiting a linear relationship between molecular weights and conversion a "living" process was established. This allowed for the straightforward synthesis of well-defined photoresist polymers. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2251,2255, 2010 [source] | ||||||||||||||||||||||||||||