- TRANSPOSITION D'OXY-COPE A TEMPERATURE AMBIANTE CATALYSEE PAR LE DICHLORURE DE PALLADIUM-BISBENZONITRILE.
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Tertiary hexa-1,5-diene-3-ols substituted on the carbon 5 (1 ; R1, R3 H) are isomerized at room temperature into δ-ethylenic ketones 2 by using 0.1 molar equivalent of the entitled palladium (II) complex.The yield of the transformation is good and the stereoselectivity is higher than 90 percent.
- Bluthe, Norbert,Malacria, Max,Gore, Jacques
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- Enantioselective synthesis of the 6,8-dioxabicyclo-[3.2.1]octane skeleton by asymmetric dihydroxylation
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Sharpless asymmetric dihydroxylation (AD) of 6-hepten-2-one with AD-mix-α followed by acidification gives (1S,5R)-5-methyl-6,8-dioxabicyclo[3.2.1]octane in moderate ee. This methodology defines a two-pot enantioselective construction of the (-)-frontalin and brevicomin skeleton from the corresponding 2-alkyl-1,3-dithiane and 5-bromo-1-hexene derivatives.
- Turpin,Weigel
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- Transformation of presumptive precursors to frontalin and ex-brevicomin by bark beetles and the West Indian sugarcane weevil (Coleoptera)
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(Z)-6-Nonen-2-one (1) has recently been shown to be the biosynthetic precursor for the aggregation pheromone exo-brevicomin (2) in mountain pine beetle (MPB) males, Dendroctonus ponderosae (Hopkins). We tested the hypotheses that (1) 6-methyl-6-hepten-2-one (3) is the biosynthetic precursor for the aggregation pheromone frontalin (4) in the spruce beetle (SB), Dendroctonus rufipennis (Kirby), and (2) that frontalin and exo-brevicomin are produced from 3 and 1, respectively, only by beetles that utilize them as aggregation pheromones. Exposure of scolytids MPB, SB, pine engraver (PE), Ips pini (Say) and Ips tridens (Mannerheim) and West Indian sugar cane weevil (WISW), Metamasius hemipterus sericeus (Olivier) to deuterio- or protio-3 invariably resulted in the production of deuterio- or protio-4. Similarly, exposure of SB, WISW and I. tridens to 1 resulted in the production of 2. We were unable to demonstrate the presence of 3 in SB volatiles, nor were we able to demonstrate the conversion of 6-methyl-5-hepten-2-one to 3 by SB. Production of enantiomerically enriched frontalin and exo-brevicomin by all the beetles exposed to respective precursors reveals widespread occurrence of nonspecific polysubstrate monooxidases in the Coleoptera.
- Perez,Gries,Gries,Oehlschlager
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- REACTION DES HEXADIENE-1,5 OLS-3 AVEC LE TRIFLUOROACETATE MERCURIQUE; TRANSPOSITION D'OXY-COPE A TEMPERATURE AMBIANTE.
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Tertiary 1,5-hexadien-3-ols 1 are transformed to δ-ethylene ketones 2 in 35-75 percent yield by treatment with one equivalent of mercuric trifluoroacetate and subsequent demercuration using sodium borohydride (Scheme I, Table).
- Bluthe, Norbert,Malacria, Max,Gore, Jacques
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- REGIOSELECTIVE SYNTHESIS OF 1-OLEFINS BY PALLADIUM-CATALYZED HYDROGENOLYSIS OF TERMINAL ALLYLIC COMPOUNDS WITH AMMONIUM FORMATE
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Various terminal allylic compounds such as allylic esters, phenyl esters, carbonates, chlorides, and vinyl epoxides react with ammonium or sodium formate to give 1-olefins with high regioselectivity by using palladium-tributylphosphine complex as a catalyst.The reaction offers a useful synthetic method for 1-olefins.
- Tsuji, Jiro,Shimizu, Isao,Minami, Ichiro
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- Stereoselective synthesis of substituted oxocene cores by Lewis acid promoted cyclization
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Substituted oxocene derivatives have been synthesized by Lewis acid catalyzed reactions of ε-hydroxyalkene and substituted aromatic aldehydes. The Cu(OTf)2-bis-phosphine catalyzed reaction typically provides substituted dihydropyran derivatives through an olefin migration followed by a Prins cyclization. The corresponding reaction catalyzed by TMSOTf or BF3·OEt2 provided eight-membered cyclic ethers (oxocenes), selectively. This methodology provides convenient access to a variety of 2,4,8-trisubstituted oxocenes in good yields and excellent diastereoselectivities.
- Ghosh, Arun K.,Tomaine, Anthony J.,Cantwell, Kelsey E.
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supporting information
p. 396 - 399
(2016/02/18)
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- A reusable unsupported rhenium nanocrystalline catalyst for acceptorless dehydrogenation of alcohols through γ-C-H activation
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Rhenium nanocrystalline particles (Re NPs), of 2 nm size, were prepared from NH4ReO4 under mild conditions in neat alcohol. The unsupported Re NPs convert secondary and benzylic alcohols to ketones and aldehydes, respectively, through catalytic acceptorless dehydrogenation (AD). The oxidant- and acceptor-free neat dehydrogenation of alcohols to obtain dihydrogen gas is a green and atom-economical process for making carbonyl compounds. Secondary aliphatic alcohols give quantitative conversion and yield. Transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Re K-edge X-ray absorption near-edge structure (XANES), and X-ray absorption fine structure (EXAFS) data confirmed the characterization of the Re NPs as metallic rhenium with surface oxidation to rhenium(IV) oxide (ReO2). Isotope labeling experiments revealed a novel γ-CH activation mechanism for AD of alcohols. Active particles: A rhenium nanoparticle (Re NP) catalyst is generated from NH4ReO4 under mild solution conditions in neat 3-octanol at 180°C. The resulting Re NPs catalyze acceptorless dehydrogenation of alcohols through a novel C-H activation pathway, and are fully recyclable. Copyright
- Yi, Jing,Miller, Jeffrey T.,Zemlyanov, Dmitry Y.,Zhang, Ruihong,Dietrich, Paul J.,Ribeiro, Fabio H.,Suslov, Sergey,Abu-Omar, Mahdi M.
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supporting information
p. 833 - 836
(2014/01/23)
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- Ultrasound promoted synthesis of (±)-8-hydroxy-5-isopropyl-8-methyl- 6(E)-nonen-2-one ((±)-solanone hydrate) and 3,7-dimethyl-2(E),7- octadienylpropionate
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A facile synthesis of the title compounds has been accomplished using Zn-Cu couple catalyzed conjugate addition of allylic halides to α,β- unsaturated ketones initiated by ultrasonic waves under aqueous conditions and Horner-Wittig reaction using ethyl α-dimethylphosphonoacetate and NaH as base in dry THF as the key steps in overall good yields.
- Singh, Vasundhara,Chaudhary, Sangeeta,Sapehiyia, Varinder,Kaur, Irvinder,Kad, Goverdhan Lal,Singh, Jasvinder
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p. 1950 - 1953
(2007/10/03)
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- Halonium ion-mediated reaction of unsaturated hydroperoxy acetals. Competition between the formation of cyclic peroxides and the migration of the methoxy (or hydroxy) group
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Monoozonolyses of dienes 2 in methanol gave in each case the corresponding unsaturated α-methoxy hydroperoxides 3. Capture of 2-alkyl- substituted cyclohexanone oxides by methanol was highly diastereoselective, thereby providing exclusively the hydroperoxides derived from attack by methanol from the less hindered face of the carbonyl oxide intermediates. Halonium ion-mediated reactions of the hydroperoxides 3 gave the novel methoxy- or hydroxy-migrated products, together with the expected halogen- substituted 1,2-dioxanes and/or 1,2-dioxepanes, the composition of the product mixture being a function of the halogenating agent utilized and the structure of 3.
- Tokuyasu, Takahiro,Masuyama, Araki,Nojima, Masatomo,McCullough, Kevin J.
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p. 1069 - 1075
(2007/10/03)
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- Reaction of some alkenols with tetrachloromethane
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The reaction of some alkenols with tetrachloromethane in the presence of a radical initiator was investigated. Regarding the effects of structural features of the starting alkenol (number and position of methyl substituents at the double bond and at the carbinol carbon atom, constitutional relationship between the double bond and the hydroxyl group) there are two possible competing reactions: addition and cyclization. In the case of the simplest alkenols (without substituents and with a more remote double bond) addition occurs; mono-and disubstituted secondary and tertiary Δ4-and Δ5-alkenols cyclize in high yields to give the corresponding cyclic ethers.
- Bugarcic, Zorica M.,Mojsilovic, Biljana,Marjanovic, Ljiljana,Konstantinovic, Stanimir
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p. 1091 - 1096
(2007/10/03)
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- Synthesis of undecan-3-one; (+/-) frontalin; (+/-)-endo-, and (+/-)-exo-brevicomin under sonochemical aqueous conditions
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Conjugate addition of 1-bromohexane (1) to 2-penten-3-one under sonochemical aqueous conditions, using Zn/Cu catalyst give undecan-3-one (3).Also, Zn-Cu catalysed conjugate addition of 1-bromo-2-methylpropene to 3-buten-2-one yield 6-methyl-6-hepten-2-one (6), which is tailored to furnish (+/-)-frontalin (7).Similarly, conjugate addition of 1-bromo-2-pentenes (8 and 8a) to 3-buten-2-one afford Z-6-nonen-2-one (9) and E-6-nonen-2-one (9a) respectively.An ice-cooled solution of 9/9a on tretament with m-chloroperbenzoic acid give (+/-)-exo-(10) and (+/-)-endo-brevicomin (10a) respectively.
- Trehan, I. R.,Singh, Jasvinder,Arora, Ajay K.,Kaur, Jasamrit,Kad, G. L.
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p. 396 - 398
(2007/10/03)
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- Ruthenium-catalysed reductive cleavage of allylic esters with formic acid and triethylamine. Application to short-step synthesis of α-hydroxy acids
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Ruthenium-catalysed reductive cleavage reactions of allylic carboxylates and carbonates with formic acid and triethylamine to give olefins were explored.As an application of the ruthenium-catalysed processes, a new synthetic route to α-hydroxy acids has been discovered.The reductive cleavage of allylic esters is considered to proceed through ?-allylruthenium intermediates. Key words: Ruthenium; Catalysis; Reductive cleavage; Allyl; Formic acid
- Maruyama, Yooichiroh,Sezaki, Takao,Tekawa, Masafumi,Sakamoto, Toshiaki,Shimizu, Isao,Yamamoto, Akio
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p. 257 - 264
(2007/10/02)
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- STEREOSELECTIVE REDUCTION OF ACETALS. A METHOD FOR REDUCTIVE GENERATION OF HETEROCYCLIC RING SYSTEMS
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A new synthetic process for the construction of oxygen-containing heterocyclic systems starting from bicyclic acetals is described.We have investigated the mechanism and the stereochemical course of the reductive cleavage of acetals.
- Ishihara, Kazuaki,Mori, Atsunori,Yamamoto, Hisashi
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p. 4595 - 4612
(2007/10/02)
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- SYNTHESIS OF THE PHEROMONES, (E)-3,7-DIMETHYL-2,7-OCTADIENYL PROPIONATE, (E)-3,7-DIMETHYL-2-OCTENE-1,8-DIOL AND FRONTALIN FROM A COMMON INTERMEDIATE
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Ketal ester 9 has been prepared in five steps from methyl levulinate 4 (scheme 1).The propionate 1, diol 2 and (+/-) frontalin 3 were prepared from ester 9 employing the routes shown in scheme 2,3 and 4 respectively.The branched chain alkenes 13 and 20 were prepared conveniently from the primary alcohols 11 and 10 following the procedure of S.Wolff.Triethyl phosphonopropionate 7 has been prepared by methylating triethylphosphonoacetate with methyl iodide in the presence of sodium hydride.
- Dhokte, U. P.,Rao, A. S.
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p. 811 - 822
(2007/10/02)
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- A New Synthesis of (+/-)-Frontalin, the Pheromone of Dentroctonus Bark Beetles
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3-Methyl-3-butenol (Ia) is converted into the corresponding iodide (Ic) via its tosylate (1b).Alkylation of α-lithioacetone dimethylhydrazone with Ic followed by oxidative hydrolysis of the resulting hydrazone (II) with NaIO4 results in the formation of 6-methyl-6-heptene-2-one (III) which on treatment with m-chloroperbenzoic acid gives the title compound (IV).
- Trehan, I. R.,Kad, G. L.,Gupta, Sangita
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p. 1243 - 1244
(2007/10/02)
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- Process for the preparation of δ-ethylenic carbonyl compounds
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Process for the preparation of δ-ethylenic carbonyl compounds of the formula: STR1 by the oxy-Cope rearrangement of a diethylenic alcohol of the formula: STR2 in which the transformation is carried out in the presence of a catalytic amount of a divalent palladium compound. In the depicted formulae R1, R4 and R6 each represent a hydrogen atom or a hydrocarbon radical, R2 represents a hydrogen atom and R3 and R5 each represent a hydrocarbon radical, or R3 and R4 together represent an alkylene radical (--CH2 --)n (wherein n is an integer from 3 to 20 inclusive) in which one or more carbon atoms can optionally carry as substituent(s) one or more alkyl radicals containing 1 to 4 carbon atoms. The carbonyl products are useful as starting materials for the preparation of compounds intended for use in pharmacy, in agriculture or perfumery.
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- A SIMPLE METHOD OF ISOMERIZATION OF THE TERMINAL DOUBLE BOND IN A TERPENE CHAIN
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The utilisability of the isomerization of the terminal double bond in terpenic compounds with trifluoroacetic acid was investigated.The results obtained were used in the synthesis of the main part of the pheromone of Quadraspidiotus perniciosus COMSTOCK, i.e. (2E)-3,7-dimethyl-2,7-octadien-1-yl propionate.
- Streinz, Ludvik,Wimmer, Zdenek,Roshka, Georgii K.,Ishchenko, Raisa I.,Romanuk, Miroslav,Kovalev, Boris G.
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p. 2174 - 2178
(2007/10/02)
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- TRANSPOSITION OXY-COPE ASSISTEE PAR LE TRIFLUOROACETATE MERCURIQUE EN QUANTITE STOECHIOMETRIQUE ET EN QUANTITE CATALYTIQUE
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Tertiary 1,5-hexadien-3-ols are transformed at room temperature into δ-ethylenic ketones in 35-90percent yields under two sets of conditions: treatment with one molar equivalent of mercuric trifluoroacetate followed by demercuration of the intermediate α-mercuro ketone with sodium borohydride; and treatment with 0.2 molar equivalent of the same salt in the presence of one molar equivalent of lithium trifluoroacetate or trifluoromethansulfonate.The reactions are highly stereoselective, the E isomer of the ketone forming 80-95percent of the product.The highest selectivity was observed under the second conditions.
- Bluthe, Norbert,Malacria, Max,Gore, Jacques
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p. 3277 - 3284
(2007/10/02)
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- Process for the preparation of 8-ethylenic carbonyl compounds
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Process for the preparation of δ-ethylenic carbonyl compounds of the formula (I) by the oxy-Cope rearrangement of a diethylenic alcohol of the formula (II), in the presence of a mercuric salt: in formulae (I) and (II), R1, R2, R
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- 1,5-Dimethyl-6,7-dioxabicyclo[3.2.1]-octane and use to control pine beetles
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1,5-Dimethyl-6,7-dioxabicyclo[3.2.1]-octane and 1,5-dimethyl-6,7-diazobicyclo[3.2.1]-oct-6-ene are synthesized. They are analogs of the western and southern pine beetle natural-pheromone, frontalin. They are useful for controlling the multiplication of these harmful insects and for limiting infestation of wooded areas by them.
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- Chemical intermediates in the preparation of oxepane compounds
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A method for synthesis of 2S*,3R*-3-benzyloxy-6,6-ethylenedioxy-2-methyl-2-(5'-hydroxy-4'-methylpentyl)-oxepane, an intermediate in the synthesis of 2S*, 2S*,3R*-6-(2"-hydroxyethylidene)-2-methyl-2-(4',8'-dimethyl-5'-oxo-7'-nonenyl)-oxepan-3-ol, one of th
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- Synthesis of 1RS,4SR,5RS-4-(4,8-dimethyl-5-hydroxy-7-nonen-1-yl)-4-methyl-3,8-dioxabicyclo[3.2.1]octane-1-acetic acid
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A method of synthesizing 1RS,4SR,5RS-4-(4,8-dimethyl-5-hydroxy-7-nonen-1-yl)-4-methyl-3,8-dioxabicyclo [3.2.1]octane-1-acetic acid. The acid is a derivative of the natural product zoapatanol, one of the active ingredients in the zoapatle plant, and is active as a utero-evacuant agent.
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- Intra- and Intermolecular Cyclization of Olefinic Tosylhydrazones under Acidic Conditions. A Facile Synthesis of Bicyclic Azoalkanes
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Tosylhydrazones of olefinic ketones and aldehydes have been observed to undergo a variety of unusual cyclizations under acidic conditions.The intramolecular version of this novel cyclization reaction has been applied in the synthesis of previously unaccessible bicyclo- and bicycloazoalkanes.Of these two bicyclic systems, the less strained system is formed with the greater ease, and in either system the intramolecular cyclization is favored by more nucleophilic olefins (isopropenyl better than vinyl).Those systems that do not undergo efficient azoalkane formation, either due to excessive ring strain or lack of olefin nucleophilicity, undergo novel intermolecular cyclizations instead.The assignments of structure to these products has been based upon 300-MHz NMR data and an X-ray crystal study of the most unusual of these condensation products, 9.From this structural information an internally consistent mechanistic framework for the formation of these products has been developed.Thus, while these intermolecular condensation reactions produce a structurally diverse set of products, all of these products seem to originate from an initial cyclization between a molecule of tosylhydrazone and its highly nucleophilic enamine tautomer.
- Wilson, R. Marshall,Rekers, John W.,Packard, Alan B.,Elder, R. C.
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p. 1633 - 1641
(2007/10/02)
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