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Total Synthesis (total + synthesis)
Kinds of Total Synthesis Terms modified by Total Synthesis Selected AbstractsNucleophilic Additions to Cyclic Nitrones en Route to Iminocyclitols , Total Syntheses of DMDP, 6-deoxy-DMDP, DAB-1, CYB-3, Nectrisine, and Radicamine BEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 17 2008Pedro Merino Abstract Highly diastereoselective nucleophilic additions to cyclic nitrones derived from L -malic acid and D -arabinose have been used for the construction of enantiomerically pure polyhydroxylated pyrrolidines. The synthetic strategy adopted was based on an oxidation/reduction protocol involving hydroxylamine/nitrone pairs and demonstrates the use of reagent- and substrate-derived stereocontrol. In most cases reactions took place with total diastereoselectivity and in quantitative yield, with no purification being necessary. By this strategy, 2-(hydroxymethyl)-, 2-(aminomethyl)-, and 2-aryl-substituted polyhydroxylated pyrrolidines have been prepared with abundant configurational diversity. The use of appropriate substrates and reagents allowed for approaches to DMDP, 6-deoxy-DMDP, DAB-1, CYB-3, nectrisine and radicamine B. Several analogues of these compounds with inverted configuration at one or more stereocenters were also prepared.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Total Syntheses of Dalesconol,A and B,ANGEWANDTE CHEMIE, Issue 30 2010Scott Anellierungsfestival: Eine Eintopf-Reaktionskaskade überführte eine sorgsam gewählte acyclische Vorstufe in die vollständige Kernstruktur der Dalesconole (siehe Schema). Weitere Schritte vervollständigten die Synthesen der beiden stark biologisch aktiven Polyketid-Naturstoffe und strukturverwandter Verbindungen. [source] ChemInform Abstract: Oxidative Friedel,Crafts Reaction and Its Application to the Total Syntheses of Amaryllidaceae Alkaloids.CHEMINFORM, Issue 29 2009Kimiaka C. Guerard 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] Concise Total Syntheses of Variolin B (Ia) and Deoxyvariolin B (Ib).CHEMINFORM, Issue 52 2005Regan J. Anderson Abstract For Abstract see ChemInform Abstract in Full Text. [source] A General and Efficient Strategy for 7-Aryloctahydroindole and cis-3a-Aryloctahydroindole Alkaloids: Total Syntheses of (.+-.)-,-Lycorane (I) and (.+-.)-Crinane(II).CHEMINFORM, Issue 52 2005Shuanhu Gao No abstract is available for this article. [source] Enantiospecific Total Syntheses of (-)-Valeranone.CHEMINFORM, Issue 41 2004A. Srikrishna Abstract For Abstract see ChemInform Abstract in Full Text. [source] Enantioselective Total Syntheses of the Cyclotryptamine Alkaloids Hodgkinsine (I) and Hodgkinsine B (II).CHEMINFORM, Issue 38 2003Jeremy J. Kodanko No abstract is available for this article. [source] First Comprehensive Bakkane Approach: Stereoselective and Efficient Dichloroketene-Based Total Syntheses of (.+-.)- and (-)-9-Acetoxyfukinanolide, (.+-.)- and (+)-Bakkenolide A, (-)-Bakkenolides III, B, C, H, L, V, and X, (.+-.)- and (-)-Homogynolide A, (.+-.)-Homogynolide B, and (.+-.)-Palmosalide C.CHEMINFORM, Issue 19 2003Timothy J. Brocksom Abstract For Abstract see ChemInform Abstract in Full Text. [source] Total Syntheses of the Marine Pyrrole Alkaloids Polycitone A and B.CHEMINFORM, Issue 3 2003Andreas T. Kreipl Abstract For Abstract see ChemInform Abstract in Full Text. [source] ChemInform Abstract: First Total Syntheses of Aeruginosin 298-A and Aeruginosin 298-B, Based on a Stereocontrolled Route to the New Amino Acid 6-Hydroxyoctahydroindole-2-carboxylic Acid.CHEMINFORM, Issue 10 2002Nativitat Valls 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: Selective Fowler Reductions: Asymmetric Total Syntheses of Isofagomine and Other 1-Azasugars from Methyl Nicotinate.CHEMINFORM, Issue 19 2001Guohua Zhao 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] Assessing Synthetic Strategies: Total Syntheses of (±)-Neodolabellane-Type DiterpenoidsCHEMISTRY - A EUROPEAN JOURNAL, Issue 27 2008Cory Valente Abstract Two strategies, namely a cross-metathesis/ring-closing metathesis and Pd-catalyzed Stille allylation/Nozaki,Hiyama,Kishi coupling, are examined for the preparation of neodolabellane-type diterpenoids 1 and 2. Whereas the first approach possessed synthetic limitations, the latter was successfully employed to provide compounds 1 and 2 in 8.8,% (14 steps) and 8,% (15 steps) overall yields, respectively. [source] Asymmetric Total Syntheses of Marine Cyclic Depsipeptide Halipeptins A,DCHEMISTRY - A EUROPEAN JOURNAL, Issue 25 2006Shouyun Yu Abstract Halipeptins A,D (1,a,d) are a family of natural cyclic depsipeptides isolated from marine sponges. Total syntheses of these four compounds are detailed in this report. The key elements in this synthesis include the elaboration of the polysubstituted decanoic acid parts by two asymmetric aldol reactions, assembly of the N -methyl-,-hydroxyisoleucine residue by using either aza-Claisen rearrangement or methylation of aspartates as the key steps, and macrocyclization at the polysubstituted decanoic acid alanine site. [source] Platinum- and Gold-Catalyzed Rearrangement Reactions of Propargyl Acetates: Total Syntheses of (,)-,-Cubebene, (,)-Cubebol, Sesquicarene and Related TerpenesCHEMISTRY - A EUROPEAN JOURNAL, Issue 11 2006Alois Fürstner Prof. Abstract Propargyl acetates, in the presence of catalytic amounts of late transition-metal salts such as PtCl2 or AuCl3, represent synthetic equivalents of ,-diazoketones. This notion is corroborated by a concise approach to various sesquiterpene natural products starting from readily available substrates. Specifically, (+)-carvomenthone (17) is converted into propargyl acetate (S)- 26 by a sequence involving Stille cross-coupling of its kinetic enol triflate 18, regioselective hydroboration/oxidation of the resulting 1,3-diene 19, and addition of an alkynyl cerium reagent to aldehyde 21 thus obtained. Since the latter step was found to be unselective, the configuration of the reacting propargyl acetate was unambiguously set by oxidation followed by diastereoselective transfer hydrogenation by using Noyori's catalyst 25. Compound (S)- 26, on treatment with PtCl2 in toluene, converted exclusively to the tricyclic enol acetate 27, which was saponified to give norcubebone 11 in excellent overall yield. The conversion of this compound into the sesquiterpene alcohol (,)-cubebol (6) was best achieved with MeCeCl2 as the nucleophile, whereas the formation of the parent hydrocarbon (,)-,-cubebene (4) was effected in excellent yield by recourse to iron-catalyzed cross coupling methodology developed in this laboratory. Since norketone 11 has previously been transformed into (,)-,-cubebene (5) as well as (,)-4-epicubebol 8, our approach constitutes formal total syntheses of these additional natural products as well. Along similar lines, the readily available propargyl acetates 1, 33 and 47 were shown to give access to 2-carene 44, sesquicarene 39, and episesquicarene 51 in excellent overall yields. In this series, however, the cycloisomerization reaction was best achieved with catalytic amounts of AuCl3 in 1,2-dichloroethane as the solvent. In addition to these preparative results, our data provide some insight into the mechanism of these remarkable skeletal rearrangement reactions. Transformations of this type are likely triggered by initial coordination of the alkyne unit of the substrate to the carbophilic transition-metal cation. Formal attack of the alkene moiety onto the resulting ,-complex engenders the formation of an electrophilic cyclopropyl carbene species which subsequently reacts with the adjacent acetate unit to give the final product. The alternative phasing of events, implying initial attack of the acetate (rather than the alkene moiety) onto the metal,alkyne complex, is inconsistent with the stereochemical data obtained during this total synthesis campaign. [source] Total Syntheses in Solution of TOAC-Labelled Alamethicin F50/5 AnaloguesCHEMISTRY & BIODIVERSITY, Issue 6 2007Cristina Peggion Abstract Total syntheses in solution of a set of four selected analogues of the 19-mer component F50/5 of alamethicin, the most extensively studied among the channel-former peptaibol antibiotics, are planned and reported. All analogues bear three Glu(OMe) residues, replacing the Gln residues at positions 7, 18, and 19 of the naturally occurring compound. Three analogues are mono-labelled with the free-radical-containing amino acid residue TOAC at the strategic positions 1, 8, or 16. The fourth analogue is bis-labelled with the same EPR-active residue at both positions,1 and 16. In the native sequence, all of the positions where TOAC replacements have been introduced are characterized by residues of Aib, the prototype of the class of helicogenic C, -tetrasubstituted , -amino acids. All of the TOAC analogues synthesized exhibit significant membrane-modifying properties. [source] Application of Selective Palladium-Mediated Functionalization of the Pyrido[3,,2,:4,5]pyrrolo[1,2- c]pyrimidine Heterocyclic System for the Total Synthesis of Variolin B and Deoxyvariolin B,EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 29 2010Alejandro Baeza Abstract The reaction of protected 3-bromo-2-(bromomethyl)-4-methoxypyrrolo[2,3- b]pyridine and tosylmethyl isocyanide (TosMIC) afforded a pyrido[3,,2,:4,5]pyrrolo[1,2- c]pyrimidine derivative in good yield. This compound was transformed through installation of the pyrimidine moiety in the C5 position, hydrolysis, and decarboxylation in an advanced intermediate for the total or formal synthesis of the naturalalkaloid variolin B. Reaction of 3-bromo-2-(bromomethyl)-4-chloropyrrolo[2,3- b]pyridine with N -tosylmethyl dichloroformimide as a synthetic TosMIC equivalent afforded trihalo-substituted pyrido[3,,2,:4,5]pyrrolo[1,2- c]pyrimidine. This compound was used in a new total synthesis of the alkaloid variolin B by selective and sequential C,N, C,C, and C,O palladium-mediated functionalization at the C9, C5, and C4 positions of the pyrido[3,,2,:4,5]pyrrolo[1,2- c]pyrimidine system. A formal synthesis of deoxyvariolin B is also described by using the same synthetic strategy. [source] Total Synthesis of Silyl-Protected Early Intermediates of Polyketide Biosynthesis,EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 16 2010Karsten Krohn Abstract The ketal- or dithioketal-protected isocoumarins 15,18 gave the corresponding 1-naphthols 21,26 in their reactions with the acetoacetate (10) or pentane-2,4-dione (19) dianions and the acetone monoanion. Subjection of the dithioketal-protected ester 28 to Baker,Venkataraman reaction conditions led to the 8-deoxy tautomeric, protected forms 29/30 of the early decaketide antibiotic intermediate 2b. However, the dithioketal protecting groups could not be removed without destruction of the molecule. Consequently the silyl-protected unstable early tri- and tetracyclic decaketide biosynthesis intermediates 37a, 37b, and 38a (precursors of angucycline and anthracycline antitumor antibiotics) were prepared through silylation of 33a and 33b, to afford 34a and 34b, and subsequent treatment with acetylacetone dianion. The ultimate synthetic goal, the silyl-protected 2,3-dialkylated naphthol derivative 41, was achieved by selective elongation of the bottom chain of the bis-silyl-protected methyl ester 36 with acetylacetone dianion. [source] Asymmetric Total Synthesis of (+)-6- epi -Castanospermine by the Stereoselective Formation of a syn,anti Acetylenic 2-Amino-1,3-diol StereotriadEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 15 2010Julien Louvel Abstract The asymmetric total synthesis of (+)-6- epi -castanospermine (1) is described herein. In this synthesis the diastereoselective addition of a racemic allenylzinc reagent to an enantiopure ,-alkoxy- tert -butylsulfinylimine is the key step and is followed by the formation of a piperidine ring by ring-closing metathesis and subsequent syn -dihydroxylation of an alkene. [source] Studies Directed Towards the Total Synthesis of (,)-DictyostatinEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 11 2010Jhillu S. Yadav Abstract The stereoselective synthesis of the three major fragments (C1,C9, C10,C17, and C19,C26) of an antimitotic marine macrolide, (,)-dictyostatin, has been achieved with a desymmetrization strategy and Oppolzer syn and anti aldol protocols as the key reactions. Takai olefination and Sonogashira coupling reactions were successfully utilized to establish the 2Z,4E -dienoate portion of the C1,C9 fragment and Stille coupling for the Z -diene core of C19,C26. [source] Short and Stereoselective Total Synthesis of ,-11,13-Didehydroguaianes and -guaianolides: Synthesis of (±)-Achalensolide and (±)-Pechueloic Acid; Revision of the Structure of (+)-Rupestonic Acid,EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 22 2009Thomas Sainte-Luce Banchelin Abstract (±)-Pechueloic acid (1), (±)-rupestonic acid (3), and (±)-achalensolide (5) (guaian-8,12-olide class) were prepared stereoselectively in only nine steps from the commercially available tropylium cation via central intermediate 6, which is used as a general and efficient precursor to bicyclo[5.3.0]decane sesquiterpenes. The method does not require function protection. It is highly regio- and stereoselective thanks to an efficient C-1 epimerization, a selective C-8,9 hydrogenation, and a stereocontrolled 1,6 conjugate addition of an acrylate equivalent. These ,-11,13-didehydroguaianes and-guaianolides are good Michael acceptors and hence biologically active. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] Stereocontrolled Preparation of Fully Substituted Cyclopentanes: Relevance to Total SynthesisEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 10 2009Brian Heasley Abstract This Microreview aims to identify important advances in the asymmetric synthesis of fully substituted five-membered carbocyclic ring systems. Recent efforts directed towards the intricate and densely functionalized core substructures of three distinct classes of cyclopentane-based natural products will be examined. Strategies featuring high levels of stereocontrol and/or conciseness in the total number of synthetic steps required to access complex natural product ring fragments are highlighted. Stereoselective Diels,Alder cycloaddition approaches to access functionalized norbornene intermediates as latent chiral cyclopentanes in the tradition of Corey's elegant prostaglandin studies are a recurring theme. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] First Asymmetric Total Synthesis of Penarolide Sulfate A1EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 36 2008Debendra K. Mohapatra Abstract Penarolide sulfate A1, with three contiguous stereogenic centers on a macrocyclic skeleton, affords promise as an ,-glucosidase inhibitor. Herein, we describe the first asymmetric total synthesis of this natural product. A stereoselective strategy for rapid assembly of the complete framework of the 30-membered macrocyclic core is delineated herein. Sequential amidation and intramolecular Sonogashira cross-coupling reactions were pivotal to the success of our efforts. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] The New Metabolite (S)-Cinnamoylphosphoramide from Streptomyces sp. and Its Total SynthesisEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 30 2008Melanie Quitschau Abstract The tunicate-associated strain Streptomyces sp. JP90 produces the unprecedented metabolite cinnamoylphosphoramide (1) among several other compounds. Structure elucidation was accomplished by NMR spectroscopic studies and efficient total synthesis. The absolute configuration at phosphorus was determined by synthesis of both enantiomers of 1 performing a resolution of the corresponding diastereomeric phosphoramides of L -phenylalanine ethyl ester. Unusual cinnamic acid derivative 1 represents the first bacterial organophosphoramide. As it matches the Schrader's formula for insecticidal organophosphates, its biological activity was investigated. A weak inhibition of acetylcholinesterase was observed in in vitro tests, and water-soluble analogues of 1 were prepared. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] First Total Synthesis of the Potent Anticancer Natural Product Dideoxypetrosynol A: Preparation of the "Skipped" (Z)-Enediyne Moiety by Oxidative Coupling of Homopropargylphosphonium YlideEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 28 2008Benjamin W. Gung Abstract Dideoxypetrosynol A is a C30 polyacetylenic alcohol with C2 symmetry. The first total synthesis of both enantiomers of the potent anti-cancer natural product (+)- and (,)-dideoxypetrosynol A is reported. The key step is an oxidative coupling of a homopropargylphosphonium ylide to prepare the "skipped" (Z)-enediyne moiety. The natural dideoxypetrosynol A was isolated as a racemic mixture as shown in structure 1. The absolute configurations of the chiral centers are established for the (+)- and (,)-enantiomers using Burgess' enzymatic resolution procedure with Pseudomonas AK lipase. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Sulfoxide-Directed Stereocontrolled Access to 2H -Chromans: Total Synthesis of the (S,R,R,R)-Enantiomer of the Antihypertensive Drug NebivololEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 12 2008M. Carmen Carreño Abstract A homochiral sulfoxide-directed reductive deoxygenation of 2-(p -tolylsulfinyl)methyl-2-chromanols allows the stereoselective formation of 2H -chromans with up to 95:5 diastereoisomeric ratio. This new methodology was appliedin a short and convergent enantioselective synthesis ofthe (S,R,R,R)-enantiomer of the antihypertensive drugNebivolol.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] An Efficient Total Synthesis of Decarestrictine D,EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 7 2008Priti Gupta Abstract An efficient total synthesis of decarestrictine D has been achieved using cross-metathesis or ring-closing metathesis and Yamaguchi macrolactonization as key steps. The stereogenic centres were generated by means of hydrolytic kinetic resolution (HKR) and Sharpless asymmetric dihydroxylation (AD). (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] First Total Synthesis of (+)-Adenophorine, a Naturally Occurring Inhibitor of Glycosidases,EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 29 2007Morwenna S. M. Pearson Abstract The first total synthesis of a naturally occurring iminosugar, (+)-adenophorine, in 14 steps from the (+)-enantiomer ofGarner's aldehyde, is reported. The strategy is based onthe preparation and functionalization of enantiomericallypure trans -6-ethyl-2-hydroxymethyl-1,2,5,6-tetrahydropyridine. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] Efficient Total Synthesis of (,)-(3S,6R)-3,6-Dihydroxy-10-methylundecanoic AcidEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 2 2007Satyendra Kumar Pandey Abstract An efficient enantioselective synthesis of (,)-(3S,6R)-3,6-dihydroxy-10-methylundecanoic acid (1) from epichlorohydrin is described. The key steps include Jacobsen's HKR, Sharpless asymmetric dihydroxylation, regioselective opening of epoxide and cyclic sulfate. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] A Chemoenzymatic, Enantioconvergent, Asymmetric Total Synthesis of(R)-Fridamycin EEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 7 2005Bernhard J. Ueberbacher Abstract A chemoenzymatic, asymmetric total synthesis of the anti-biotic (R)-fridamycin E has been accomplished following a biocatalytic deracemization procotol. The key step comprises the construction of the chiral side-chain from a functionalized rac -2,2-disubstituted oxirane via a kinetic resolution/stereoinversion sequence without formation of the undesiredstereoisomer. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Total Synthesis without Protection: Three-Step Synthesis of Optically Active Clavicipitic Acids by a Biomimetic RouteEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 6 2004Yuusaku Yokoyama Abstract A three-step synthesis of a mixture of optically active cis - and trans -clavicipitic acids 6, which are ergot alkaloids, was achieved, starting from 4-bromoindole (7) and dl -serine (dl - 2). This short synthesis was made possible by omitting the protection and deprotection steps from the synthetic route. The key step was the spontaneous cyclization of 4-vinyltryptophan (10) formed from the Heck reaction of 4-bromotryptophan (8) with 2-methyl-3-buten-2-ol (9) in aqueous media. During this investigation, we also found that the palladium-catalyzed reaction of 8 with 9 showed an interesting pH dependence; under strongly basic conditions, the Heck reaction occurred to give a C4 -vinylated product 10, whereas an N -allylated product 19b was formed under neutral or weakly basic conditions. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source] | |||||||||||||||||||||||||