- Studies in Cephalotaxus Alkaloids. Stereospecific Total Synthesis of Homoharringtonine
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The alkaloid ester homoharringtonine (2) was synthesized stereospecifically via the Reformatsky reaction of methyl α-bromoacetate with cephalotaxyl pyruvate (16) obtained by esterification of cephalotaxine with acid chloride derived from 15.The preparations of 2 and its unsaturated derivative 13 are described in detail.Possible explanations of the steric requirements in the esterification of cephalotaxine and of the steric outcome of the Reformatsky reaction leading to 2 and 13 are advanced.
- Hiranuma, Sayoko,Shibata, Misako,Hudlicky, Tomas
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- Total synthesis and biological evaluation of the natural product (-)-cyclonerodiol, a new inhibitor of IL-4 signaling
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In a screening program of natural compounds from fungi, the known cyclopentanoid sesquiterpene (-)-cyclonerodiol was identified as a specific inhibitor of the IL-4 induced STAT6 signaling pathway (IC50 = 9.7 μM) which is required for the differentiation of naive CD4 T cells to T helper type 2 (Th2) lymphocytes. As many allergic conditions, including allergic asthma and atopic diseases, are driven by an excessive Th2 response, STAT6 is a promising target for the development of new therapeutics. The compound was synthesized in six steps from (-)-linalool using an epoxide radical cyclization as the key step. This journal is
- Langhanki, Jens,Rudolph, Kristina,Erkel, Gerhard,Opatz, Till
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- Progress toward the total synthesis of bacchopetiolone: Application of a tandem aromatic oxidation/Diels-Alder reaction
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A stereoselective synthesis of the bacchopetiolone (1) carbocyclic core using a tandem phenolic oxidation/Diels-Alder reaction is described.
- Berube, Amelie,Drutu, Ioana,Wood, John L.
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- Towards the total synthesis of vibsanin E, 15-O-methylcyclovibsanin B, 3-hydroxyvibsanin E, furanovibsanin A, and 3-O-methylfuranovibsanin A
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Studies detailing synthetic approaches to a variety of biosynthetically related vibsanin-type diterpenes (i.e. vibsanin E, 15-O-methylcyclovibsanin B, 3-hydroxy-vibsanin E, furanovibsanin A, and 3-O-methylfuranovibsanin A) are discussed. Biogenetically modelled approaches are coupled with an investigation of classical and modern six- to seven-membered ring-expansion protocols, which gain access to the central core of these natural products. Wiley-VCH Verlag GmbH & Co. KGaA, 2006.
- Schwartz, Brett D.,Tilly, David P.,Heim, Ralf,Wiedemann, Stefan,Williams, Craig M.,Bernhardt, Paul V.
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- Photoredox-Catalyzed Cascade Reactions Involving Aryl Radical: Total Synthesis of (±)-Norascyronone A and (±)-Eudesmol
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Herein, we have developed two types of photoredox-catalyzed cascade reactions using diaryliodonium salts for the concise synthesis of norascyronone A and β-eudesmol. A rationally designed photoredox-catalyzed arylation/cyclization/Friedel-Crafts cascade reaction of enone was exploited to generate the norascyronone polycyclic skeleton. A visible-light-induced radical cyclization/acyloxy-migration reaction was explored to forge the decalin skeleton of eudesmol, and mechanistic studies indicated the reaction was initiated by one-electron oxidation of the enol ester.
- Xu, Ze-Jun,Liu, Xu-Yuan,Zhu, Ming-Zhu,Xu, Yu-Liang,Yu, Yue,Xu, Hai-Ruo,Cheng, Ai-Xia,Lou, Hong-Xiang
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supporting information
p. 9073 - 9077
(2021/12/06)
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- Incorporation of a FRET pair within a phosphonate diester
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Cell-cleavable protecting groups are an effective tactic for construction of biological probes because such compounds can improve problems with instability, solubility, and cellular uptake. Incorporation of fluorescent groups in the protecting groups may afford useful probes of cellular functions, especially for payloads containing phosphonates that would be highly charged if not protected, but little is known about the steric or electronic factors that impede release of the payload. In this report we present a strategy for the synthesis of a coumarin fluorophore and a 4-((4-(dimethylamino)phenyl)diazenyl)benzoic acid (DABCYL) ester chromophore incorporated as a FRET pair within a single phosphonate. Such compounds were designed to deliver a BTN3A1 ligand payload to its intracellular receptor. Both final products and some synthetic intermediates were evaluated for their ability to undergo metabolic activation in γδ T cell functional assays, and for their photophysical properties by spectrophotometry. One phosphonate bearing a DABCYL acyloxyester and a novel tyramine-linked coumarin fluorophore exhibited strong, rapid, and potent cellular activity for γδ T cell stimulation and also showed FRET interactions. This strategy demonstrates that bioactivatable phosphonates containing FRET pairs can be utilized to develop probes to monitor cellular uptake of otherwise charged payloads.
- Harmon, Nyema M.,Huang, Xueting,Hsiao, Chia-Hung Christine,Wiemer, Andrew J.,Wiemer, David F.
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- Direct Synthesis of Enones by Visible-Light-Promoted Oxygenation of Trisubstituted Olefins Using Molecular Oxygen
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A one-step synthesis of enones from olefins is described. The reaction was performed under visible-light irradiation in the presence of molecular oxygen and a photocatalyst. The reaction proceeded with various types of trisubstituted olefins to give enones in good yields with high regioselectivity. In particular, oxygen- and nitrogen-containing functional groups, heteroaromatic rings, and cyclopropanes were tolerated. Mechanistic studies and previous reports indicated that the active oxygen species generated in the reaction system is singlet oxygen.
- Harada, Shinji,Matsuda, Daiki,Morikawa, Takahiro,Nishida, Atsushi
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supporting information
p. 1372 - 1377
(2020/10/02)
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- AuCl3-Catalyzed Ring-Closing Carbonyl–Olefin Metathesis
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Compared with the ripeness of olefin metathesis, exploration of the construction of carbon–carbon double bonds through the catalytic carbonyl–olefin metathesis reaction remains stagnant and has received scant attention. Herein, a highly efficient AuCl3-catalyzed intramolecular ring-closing carbonyl–olefin metathesis reaction is described. This method features easily accessible starting materials, simple operation, good functional-group tolerance and short reaction times, and provides the target cyclopentenes, polycycles, benzocarbocycles, and N-heterocycle derivatives in good to excellent yields.
- Wang, Rui,Chen, Yi,Shu, Mao,Zhao, Wenwen,Tao, Maoling,Du, Chao,Fu, Xiaoya,Li, Ao,Lin, Zhihua
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supporting information
p. 1941 - 1946
(2020/02/11)
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- Visible-Light Mediated Hydrosilylative and Hydrophosphorylative Cyclizations of Enynes and Dienes
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Described herein is a visible-light mediated intermolecular radical cyclization approach to access heterocycles. Heteroatom radicals, such as silicon and phosphorus atom radicals, were generated via direct hydrogen atom abstraction by the photoexcited catalyst species with hydro-silanes and phosphine oxides. The radical addition/cyclization/HAT (hydrogen atom transfer) reaction sequences of 1,6-enynes and 1,6-dienes were highly efficient delivering the desired heterocycles in good yields.
- Chen, Xiaoyun,Hou, Hong,Shi, Yaocheng,Xu, Yue,Yan, Chaoguo,Yang, Haibo,Zhu, Shaoqun
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supporting information
(2020/03/04)
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- Potent double prodrug forms of synthetic phosphoantigens
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Phosphoantigens are ligands of BTN3A1 that stimulate anti-cancer functions of γδ T cells, yet the potency of natural phosphoantigens is limited by low cell permeability and low metabolic stability. Derivatives of BTN3A1 ligand prodrugs were synthesized that contain an acetate-protected allylic alcohol and act as doubly protected prodrugs. A novel set of phosphonates, phosphoramidates, and phosphonamidates has been prepared through a new route that simplifies synthesis and postpones the point of divergence into different prodrug forms. One of the new prodrugs, compound 11, potently stimulates γδ T cell proliferation (72 h EC50 = 0.12 nM) and interferon γ response to loaded leukemia cells (4 h EC50 = 19 nM). This phosphonamidate form was > 900x more potent than the corresponding phosphoramidate, and the phosphonamidate form was also significantly more stable in plasma following acetate hydrolysis. Therefore, prodrug modification of phosphonate butyrophilin ligands at the allylic alcohol can both facilitate chemical synthesis and improve potency of γδ T cell stimulation.
- Harmon, Nyema M.,Hsiao, Chia-Hung Christine,Huang, Xueting,Schladetsch, Megan A.,Wiemer, Andrew J.,Wiemer, David F.
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- An Intramolecular Cycloaddition Approach to the Kauranoid Family of Diterpene Metabolites
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Synthetic studies toward the ent-kauranoid family of diterpene natural products are reported. An intramolecular (4 + 3) cycloaddition allows the direct elaboration of diverse natural product frameworks, encompassing a challenging bicyclo[3.2.1]octane core. The established routes comprise only a few synthetic operations (3-5 steps), transforming a range of simple starting materials into the tetracyclic scaffolds that are commonly found in many ent-kaurene metabolites.
- Callebaut, Brenda,Hullaert, Jan,Van Hecke, Kristof,Winne, Johan M.
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supporting information
p. 310 - 314
(2019/01/10)
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- Domino Aryne Annulation via a Nucleophilic-Ene Process
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1,2-Benzdiyne equivalents possess the unique property that they can react with two arynophiles through iteratively generated 1,2- and 2,3-aryne intermediates. Upon rational modification on the second leaving group of these aryne precursors, a domino aryne annulation approach was developed through a nucleophilic-ene reaction sequence. Various benzo-fused N-heterocyclic frameworks were achievable under transition metal-free conditions with a broad substrate scope.
- Xu, Hai,He, Jia,Shi, Jiarong,Tan, Liang,Qiu, Dachuan,Luo, Xiaohua,Li, Yang
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supporting information
p. 3555 - 3559
(2018/03/21)
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- Synthesis and biological evaluation of 1,2-disubstituted 4-quinolone analogues of Pseudonocardia sp. Natural products
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A series of analogues of Pseudonocardia sp. natural products were synthesized, which have been reported to possess potent antibacterial activity against Helicobacter pylori and induce growth defects in Escherichia coli and Staphylococcus aureus. Taking inspiration from a methodology used in our total synthesis of natural products, we applied this methodology to access analogues possessing bulky N-substituents, traditionally considered to be challenging scaffolds. Screening of the library provided valuable insights into the structure-activity relationship of the bacterial growth defects, and suggested that selectivity between bacterial species should be attainable. Furthermore, a structurally related series of analogues was observed to inhibit production of the virulence factor pyocyanin in the human pathogen Pseudomonas aeruginosa, which may be a result of their similarity to the Pseudomonas quinolone signal (PQS) quorum sensing autoinducer. This provided new insights regarding the effect of N-substitution in PQS analogues, which has been hitherto underexplored.
- Geddis, Stephen M.,Coroama, Teodora,Forrest, Suzanne,Hodgkinson, James T.,Welch, Martin,Spring, David R.
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supporting information
p. 2680 - 2688
(2018/11/03)
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- Palladium-Catalyzed Carbocyclizations of Unactivated Alkyl Bromides with Alkenes Involving Auto-tandem Catalysis
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The development of a general catalytic system for the palladium-catalyzed carbocyclization of unactivated alkyl bromides with alkenes is described. This approach uses a commercially available bisphosphine ligand and avoids the use of carbon monoxide atmosphere present in prior studies involving alkyl iodides. Detailed mechanistic studies of the transformation are performed, which are consistent with auto-tandem catalysis involving atom-transfer radical cyclization followed by catalytic dehydrohalogenation. These studies also suggest that reactions involving alkyl iodides may proceed through a metal-initiated, rather than metal-catalyzed, radical chain process.
- Venning, Alexander R. O.,Kwiatkowski, Megan R.,Roque Pe?a, Joan E.,Lainhart, Brendan C.,Guruparan, Akil A.,Alexanian, Erik J.
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supporting information
p. 11595 - 11600
(2017/08/30)
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- Host-Catalyzed Cyclodehydration–Rearrangement Cascade Reaction of Unsaturated Tertiary Alcohols
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The Br?nsted acidic resorcin[4]arene hexamer can be applied as an effective catalyst in the dehydrative cyclization and subsequent rearrangement of unsaturated tertiary alcohols. This is the first report on catalyzing such a reaction with a Br?nsted acid. Scope and limitations of this cyclopentene-forming reaction sequence are presented. Furthermore, substrate-selective conversion as well as competitive inhibition are described and provide evidence that the reactions proceed within the cavity of the self-assembled structure. Additionally, a cyclobutanone-forming intramolecular hydride transfer of an encapsulated cyclopropyl acetate is reported. (Figure presented.).
- Catti, Lorenzo,P?thig, Alexander,Tiefenbacher, Konrad
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supporting information
p. 1331 - 1338
(2017/04/18)
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- The synthesis of quinolone natural products from pseudonocardia sp.
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The synthesis of four quinolone natural products from the actinomycete Pseudonocardia sp. is reported. The key step involved a sp2-sp3 Suzuki-Miyaura reaction between a common boronic ester lateral chain and various functionalised quinolone cores. The quinolones slowed growth of E. coli and S. aureus by inducing extended lag phases. The total synthesis of four quinolone natural products is reported. The quinolones were synthesised in a highly efficient and direct manner from various readily prepared quinolone cores and a common boronic ester lateral chain. The key step involved a challenging sp2-sp3 Suzuki-Miyaura reaction.
- Salvaggio, Flavia,Hodgkinson, James T.,Carro, Laura,Geddis, Stephen M.,Galloway, Warren R. J. D.,Welch, Martin,Spring, David R.
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supporting information
p. 434 - 437
(2016/02/18)
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- Copper-Catalyzed Enantioselective Conjugate Addition to α,β-Unsaturated Aldehydes with Various Organometallic Reagents
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β-Substituted aldehydes constitute a very important class of compounds found in nature. Synthesis of this motif can be envisioned by C-C bond formation on enals. For this purpose, we report herein the development of enantioselective copper-catalyzed conjugate addition of various organometallic reagents to α,β-unsaturated aldehydes with (R)-H8BINAP, (R)-TolBINAP, and (R)-SEGPHOS as chiral ligands. Three sets of conditions were successfully developed and several enals were used. Reactivity and regio- and enantioselectivities were strongly dependent on reaction conditions and substrates. Good to excellent regio- and enantioselectivities were obtained with zinc reagents R2Zn and aluminum reagents R3Al. However, the asymmetric conjugate addition of Grignard reagents afforded only moderate to good regio- and enantioselectivities.
- Goncalves-Contal, Sylvie,Gremaud, Ludovic,Palais, La?titia,Babel, Lucille,Alexakis, Alexandre
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supporting information
p. 3301 - 3308
(2016/09/12)
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- Sequential O-H/C-H bond insertion of phenols initiated by the gold(I)-catalyzed cyclization of 1-bromo-1,5-enynes
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The development of a sequential O-H/C-H bond functionalization of phenols initiated by the cationic gold(I)-catalyzed cyclization of 1-bromo-1,5-enynes to produce (2-bromocyclopent-2-en-1-yl)phenols is reported. This unprecedented domino transformation efficiently proceeds under mild conditions (5 mol % of (t-Bu)3PAuNTf2, CH2Cl2, 0-23 °C) via an intermediate aryl alkyl ether which collapses at ambient temperature to undergo a 1,2-hydride shift followed by C-H insertion of the phenol.
- Speck, Klaus,Karaghiosoff, Konstantin,Magauer, Thomas
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supporting information
p. 1982 - 1985
(2015/04/27)
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- Copper-catalyzed asymmetric conjugate addition with chiral SimplePhos ligands
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SimplePhos ligands represent a novel class of monodentate chiral ligands based on a chiral amine moiety and flexible diaryl groups on the phosphorous atom. They can be easily prepared by two different pathways and they can be highly functionalised. Herein we report the copper-catalysed asymmetric conjugate addition of diethyl zinc and trialkylaluminium reagents with SimplePhos ligands, which gives high enantioselectivity with cyclic enones, acyclic enones and nitro-olefins, with up to 98.6 % ee. Of particular interest is the reaction of trialkylaluminium reagents with a wide range of 3substituted enones, thus allowing the formation of stereogenic quaternary carbon centres.
- Palais, Laetitia,Alexakis, Alexandre
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supporting information; experimental part
p. 10473 - 10485
(2010/05/02)
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- Process for Preparing 2-Methoxycarbonylmethyl-6,6-Dimethyl-2-Tetrahydropyran Carboxylic Acid
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Process for preparing 2-methoxycarbonylmethyl-6,6-dimethyl-2-tetrahydropyran carboxylic acid (I) comprising: a) Reaction of 5-bromo-2-methyl-2-pentene (III) with magnesium and then diethyloxalate to obtain ethyl-2-oxo-6-methyl-5-heptenoate (IV); b) Reaction of ethyl-2-oxo-6-methyl-5-heptenoate (IV) with an alkali amide and methyl acetate to obtain ethyl-2-methoxycarbonylmethyl-2-hydroxy-6-methyl-5-heptenoate (V); c) Reaction of ethyl-2-methoxycarbonylmethyl-2-hydroxy-6-methyl-5-heptenoate (V) with an alkali metal hydroxide to obtain the corresponding 2-carboxymethyl-2-hydroxy-6-methyl-5-heptenoic acid (VI); d) Cyclisation of 2-carboxymethyl-2-hydroxy-6-methyl-5-heptenoic acid (VI) with formic acid to give 2-carboxymethyl-6,6-dimethyl-2-tetrahydropyrancarboxylic acid (VII); e) Monoesterification of 2-carboxymethyl-6,6-dimethyl-2-tetrahydropyrancarboxylic acid (VII) to 2-methoxycarbonylmethyl-6,6-dimethyl-2-tetrahydropyran carboxylic acid (I), characterised in that in stage (e) the 2-methoxycarbonylmethyl-6,6-dimethyl-2-tetrahydropyran carboxylic acid (I) is purified by means of the formation of the corresponding salt with cyclohexylamine (IA).
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(2009/03/07)
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- PROCESS FOR PREPARING 2-METHOXYCARBONYLMETHYL-6,6-DIMETHYL-2- TETRAHYDROPYRAN CARBOXYLIC ACID
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Process for preparing 2-methoxycarbonylmethyl-6,6-dimethyl-2-tetrahydropyran carboxylic acid (I) comprising: a) Reaction of 5-bromo-2-methyl-2-pentene (III) with magnesium and then diethyloxalate to obtain ethyl-2-oxo-6-methyl-5-heptenoate (IV); b) Reaction of ethyl-2-oxo-6-methyl-5-heptenoate (IV) with an alkali amide and methyl acetate to obtain ethyl-2- methoxycarbonylmethyl^-hydroxy-θ-methyl- 5-heptenoate (V); c) Reaction of ethyl-2- methoxycarbonylmethyl-2-hydroxy-6-methyl-5-heptenoate (V) with an alkali metal hydroxide to obtain the corresponding 2-carboxymethyl- 2-hydroxy-6-methyl-5-heptenoic acid (Vl); d) Cyclisation of 2-carboxymethyl-2-hydroxy-6-methyl-5-heptenoic acid (Vl) with formic acid to give 2-carboxymethyl-6,6-dimethyl-2-tetrahydropyrancarboxylic acid (VII); e) Monoesterification of 2-carboxymethyl-6,6-dimethyl-2- tetrahydropyrancarboxylic acid (VII) to 2-methoxycarbonylmethyl-6,6-dimethyl- 2-tetrahydropyran carboxylic acid (I), characterised in that in stage (e) the 2-methoxycarbonylmethyI-6,6-dimethyl-2- tetrahydropyran carboxylic acid (I) is purified by means of the formation of the corresponding salt with cyclohexylamine (IA).
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Page/Page column 7
(2010/11/25)
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- METHOD FOR TREATING ANXIETY WITH MUSCARINIC CHOLINERGIC RECEPTOR AGONISTS
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The present invention relates a method for treating anxiety using azacyclic and azabicyclic pyrazine compounds.
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- Scavenger assisted combinatorial process for preparing libraries of tertiary amine compounds
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This invention relates to a novel solution phase process for the preparation of tertiary amine combinatorial libraries. These libraries have utility for drug discovery and are used to form wellplate components of novel assay kits.
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- An Intramolecular Prins Double Cyclization Catalyzed by Silyl Triflates
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Several intramolecular Prins double cyclizations are reported. The 2-alkyl 5-hepten-1,2-diols and their analogues, 9-11, were prepared and oxidized to the aldehydes 6-8 under Swern conditions. Treatment of these α-hydroxy aldehydes with TBSOTf and a hindered base gave the products of an intramolecular Prins double cyclization, namely the 7-(silyloxy)-2-oxabicyclo[2.2.1]heptanes, 17- 19, in 84-92% yield. These compounds were formed as single diastereomers with only the anti silyl ethers being obtained. The cyclizations occur when five-membered rings are being formed and when the initially formed cation is highly stabilized. Other substrates do not cyclize, e.g., when the α-hydroxy aldehydes 20-22, prepared from 26-28, are treated under similar conditions, none of the corresponding cyclization products, 23-25, were obtained.
- Jung, Michael E.,Angelica, Steve,D'Amico, Derin C.
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p. 9182 - 9187
(2007/10/03)
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- Use of azacyclic or azabicyclic pyrazine compounds for treating anxiety
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The present invention relates a method for treating anxiety using azacyclic and azabicyclic pyrazine compounds.
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- Termite trail attractants: New synthesis of racemic (E)-α-, (Z)-α- and β-bisabolenes
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Racemic (E)-α-bisabolene (E)(1) was synthetized starting from 4-methyl-3-cyclohexenecarboxylic acid (3) by a reaction sequence involving the Pd(0)-catalyzed cross-coupling reaction between the (E)-2-methyl-1-alkenyltrimethylstannane 8 and 3-methyl-2-buten-1-yl acetate (9). Three different procedures, in which a common precursor was used as key intermediate, were tested for the synthesis of racemic (Z)-α-bisabolene (Z)(1). The best one, which involved the reaction between bromide 18 and lithium dialkenylcuprate 19, afforded a mixture of (Z)- and (E)-1 in a 93:7 molar ratio, respectively. Finally, racemic β-bisabolene (2) was synthetized by a simple reaction sequence involving the Zr-promoted methylenation of ketone 22 prepared from 3.
- Argenti,Bellina,Carpita,Dell'Amico,Rossi
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p. 3167 - 3188
(2007/10/02)
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- Hemisynthesis of (20S,24R)-20,24-epoxy-3β,16β,25-trihydroxy-6-oxo-5α-cholestane 16-acetate from diosgenin
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The title compound which was isolated as its 3β-sophoroside from the defensive secretion of Chrysomela varians (Coleoptera: Chrysomelidae) has been synthesized from diosgenin in 8 steps.
- Tavares, Regina,Randoux, Thierry,Braekman, Jean-Claude,Daloze, Desire
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p. 5079 - 5090
(2007/10/02)
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- Nitro alkanes in organic synthesis: An efficient stereoselective synthesis of (+)-trans whisky lactone and (+)-eldanolide from nitro alkane synthons and using bakers' yeast reduction as the key step
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An efficient route using nitroalkane synthon 3a and 3b for the synthesis of optically pure R-(+)-trans whisky lactone, (+)-9 and R-(+)-eldanolide, (+)-10 is described. In a key step, bakers' yeast reduction is employed to get the required chirality.
- Sarmah, Bhabani K.,Barua, Nabin C.
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p. 2253 - 2260
(2007/10/02)
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- ASYMMETRIC SYNTHESIS OF PERMETHRIC ACID. STEREOCHEMISTRY OF CHIRAL COPPER CARBENOID REACTION.
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The most effective optical isomer (1R-cis) of permethric acid (2, R=H), a potent intermediate in the production of synthetic pyrethroid, was enantioselectively prepared.
- Aratani, Tadatoshi,Yoneyoshi, Yukio,Nagase, Tsuneyuki
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p. 685 - 688
(2007/10/02)
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- Copper(I)-Mediated Synthesis of cis-Isoprenoids. Models for Natural Rubber
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Two copper(I)-mediated routes for the preparation of all-cis-2,6,10-trimethyl-2,6,10-dodecatriene are investigated.Reaction of the Grignard reagent derived from 1-bromo-4-methylpent-3-ene with CuBr, and then with excess propyne, gave a vinylcopper intermediate which could be alkylated with 1-iodo-3-methylpent-3-ene, to afford the required triene stereospecifically cis- in 28percent yield.Iodination of the same intermediate and subsequent conversion to 1-bromo-4,8-dimethyl-3,7-nonadiene is shown to occur with retention of configuration, so allowing the iterative construction of cis-isoprenoids.This vinylcopper-based route is shown to be also applicable to the synthesis of larger cis-isoprenoids.In contrast, the CuI-modified coupling reaction of the Grignard reagent from 1-chloro-2-methylbut-2-ene with neryl chloride gave a mixture of triene isomers.
- Parr, William J. E.
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p. 4101 - 4130
(2007/10/02)
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- Synthetic Applications of Metal Halides.Conversion of Cyclopropylmethanols into Homoallylic Halides.
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Magnesium and beryllium halides in refluxing diethyl ether effect the transformation of cyclopropylmethanols into homoallylic halides,in contrast to several other metal halides and Lewis acid/nucleophile combinations which were examined.Magnesium bromide and iodide are particularly effective: conditions are mild,yields are high,and little or no byproducts are formed.Tertiary and benzylic alcohols are more reactive than secondary alcohols,while the latter are converted into E homoallylic halides with high stereoselectivity.Cyclopropylmethanol itself fails to react.In the cases of magnesium halide reactions with bicyclo-2-hexanol and bicyclo-2-heptanol,addition of an equimolar amount of zinc halide not only caused substantial rate enhancement but also increased regioselectivity.
- McCormick, J.P.,Barton, Donald L.
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p. 2566 - 2570
(2007/10/02)
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- Insect Juvenile Hormone Analogues: Part VIII - Synthesis of Some Functionalised Analogues of Geranyl Aromatic Ethers
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Synthesis of various amides (XV-XX) involving coupling of isohexenylamine (V) with different phenoxy acids (VI-XI) is described.Preparation of the amides (XXI-XXIII) of α-and β-naphthoxyacetic acids (XII, XIII) and 2-benzothiazolemercatoacetic acid (XIV) is also described.These compounds have been tested against the common Indian red cotton bug for their juvenile hormone activity.
- Vig, O. P.,Trehan, I. R.,Kumari, Sarla,Grewal, M. S:
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p. 784 - 786
(2007/10/02)
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