- (4E)-dehydrocitrals [(2E,4E)- and (2Z,4E)3,7-dimethyl-2,4,6-octatrienals] from acarid mite histiogaster sp. A096 (Acari: Acaridae)
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A mixture of two monoterpenes was obtained as the opisthonotal gland secretion from unidentified Histiogaster sp. A096 (Acari: Acaridae), and their structures were elucidated to be (4E)-dehydrocitrals [(2E,4E)- and (2Z,4E)-3,7-dimethyl-2,4,6-octatrienals] by GC/MS, GC/FT-IR, UV and 1H-NMR spectra. Both isomers of (4E)-dehydrocitral prepared by syntheses in 4 steps from 3-methyl-2-butenal with 34.2% yields (based on the ylide) were separated by column chromatography into the (2E,4E)- and (2Z,4E)-3,7-dimethyl-2,4,6-octatrienal. Mass spectra together with GC retention times of the purified natural (4E)-dehydrocitrals were identical with those of synthetic (2E,4E)-3,7-dimethyl-2,4,6-octatrienal and (2Z,4E)-3,7-dimethyl-2,4,6-octatrienal. The geometry at the 2-C position of both synthetic (4E)-dehydrocitrals was confirmed by NOESY analyses. This is the first identification of (4E)-dehydrocitrals from the animal kingdom.
- Hiraoka, Hiroyuki,Mori, Naoki,Nishida, Ritsuo,Kuwahara, Yasumasa
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Read Online
- Method for synthesizing methyl heptenone from methyl butynol
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The invention provides a method for synthesizing methyl heptenone from methyl butynolwhich. The method comprises the following steps: carrying out a rearrangement reaction on methyl butynol and 2-alkoxy propylene under the action of an acid catalyst to obtain a mixture of allenyl ketone and methylheptadienone; and carrying out selective hydrogenation on the mixture under the action of a hydrogenation catalyst to obtain the methyl heptenone product. The synthesis route is novel, firstly, the rearrangement reaction is firstly carried out to obtain allenyl ketone and methylheptadienone intermediates, and the problem of low selectivity of enol synthesis by alkynol hydrogenation is avoided; sulfonic acid resin and a Lewis acid are used for a synergistic catalytic reaction, so that the rearrangement reaction condition is mild; then hydrogenation of allenyl ketone and methylheptadienone is catalyzed by using a Lindelar catalyst and taking an alkali and quinoline as assistants so as to obtainthe methyl heptenone with high selectivity; and the method has the advantages of readily available starting raw materials, low price, high total yield of the route, good cost advantage and potential application prospect.
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Page/Page column 5-11
(2020/05/02)
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- Relay Catalysis to Synthesize β-Substituted Enones: Organocatalytic Substitution of Vinylogous Esters and Amides with Organoboronates
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Organocatalysis was shown to facilitate conjugate additions to vinylogous esters and amides for the first time. Subsequent elimination of a β-alcohol or amine provided π-conjugated β-substituted enones. Remarkably, nucleophile addition to the electron-rich vinylogous substrates is more rapid than classical enones, forming monosubstituted products. A doubly organocatalytic (organic diol and methyl aniline) conjugate addition synthesized the products directly from alkynyl ketones. Both of these catalytic transformations are orthogonal to transition metal catalysis, allowing for good yields, easily accessible or commercially available reagents, high selectivity, reagent recovery and recyclability, facile scalability, and exceptional functional group tolerance.
- Sundstrom, Sasha,Nguyen, Thien S.,May, Jeremy A.
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supporting information
p. 1355 - 1359
(2020/02/13)
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- Method for synthesizing alpha,gamma-unsaturated dienone from propargyl alcohol and catalyst system used for method
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The invention discloses a method for synthesizing alpha,gamma-unsaturated dienone from propargyl alcohol and a catalyst system used for the method. The method comprises the following steps: (1) a Saucy-Marbet reaction is carried out on propargyl alcohol and alkoxy propylene under the action of an acidic resin catalyst to obtain an allenyl ketone intermediate; and (2) a heterogeneous reaction is carried out on the allenyl ketone under the action of a solid base catalyst to obtain the alpha,gamma-unsaturated dienone product. The method disclosed by the invention has the main advantages that solid catalysts are adopted in the two steps of reactions, the catalyst activity is high, and the catalysts are easy to separate from products. Compared with a separation process in an existing homogeneous acid catalysis process, the separation process in the method provided by the invention is greatly simplified. Secondly, the acid resin catalyst and solid base catalyst adopted in the method both canbe continuously recycled, so that the cost is low, and the method is economical and feasible and is superior to the existing known process.
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- Palladium-Catalyzed Cleavage of α-Allenylic Aryl Ether toward Pyrazolemethylene-Substituted Phosphinyl Allenes and Their Transformations via Alkenyl C-P(O) Cleavage
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A palladium-catalyzed two-component coupling of allenylphosphine oxides with conjugated N-tosylhydrazones is revealed. For the first time, the cleavage of α-allenylic aryl ether toward pyrazolemethylene-substituted phosphinyl allenes enabled facile synthesis of combined motifs with pyrazole and allene. Moreover, the obtained adducts could be easily transformed to potential bioactive multifunctionalized phosphinates via a novel alkenyl C-P(O) cleavage.
- Zhu, Jie,Mao, Mao,Ji, Huan-Jing,Xu, Jiang-Yan,Wu, Lei
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supporting information
p. 1946 - 1949
(2017/04/28)
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- Gold-catalyzed cycloisomerization of cyclopropyl alkynyl acetates: A versatile approach to 5-, 6-, and 7-membered carbocycles
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Nonclassical chirality transfer? Depending on the substitution pattern of propargyl acetates, a gold-catalyzed homologous Rautenstrauch reaction generates either 5- or 6-membered ring systems (see scheme). The stabilization of cationic intermediates is crucial for this reaction to succeed. The underlying principle for the good chirality transfer observed could be gold-stabilized nonclassical carbocations having configurational stability.
- Zou, Yue,Garayalde, David,Wang, Quanrui,Nevado, Cristina,Goeke, Andreas,Ito, Yoshihiko
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supporting information; experimental part
p. 10110 - 10113
(2009/05/30)
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- Preparation of γ, δ-unsaturated ketones by the carroll reaction in cyclic carbonates or γ-lactones
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A process for preparing γ,δ-unsaturated ketones by a) reacting vinylcarbinols or propargyl alcohols with alkyl acetoacetates or diketene and b) thermally rearranging the resulting acetoacetates in the presence or absence of an aluminum catalyst to γ,δ-unsaturated ketones (Carroll reaction), wherein step a) and/or step b) is carried out in a cyclic carbonate of the formula I or a γ-lactone of the formula II STR1 where R1, R2 and R3 are H, or lower alkyl and R4 is H, lower alkyl, phenyl or methoxymethyl, as solvent.
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- New Insights on the Reaction of Alkyl 3-Oxo-4-(triphenylphosphoranylidene)butanoate and Aldehydes under Concentrated Condensation Conditions. One-Pot Synthesis of Highly functionalised 6-Oxocyclohex-4-ene-1,3-dicarboxylates
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New annulation methodologies for the construction of substituted cyclohex-2-enones are important in organic synthesis. In this paper wee describe a new one-pot synthesis of substituted cyclohexenonedicarboxylates in maximum yield of 52 percent from the condensation of alkyl 3-oxo-4-(triphenylphosphoranylidene)-butanoate 1 and aldehydes.
- Moorhoff, Cornelis M.,Schneider, David F.,Winkler, Dave
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p. 3461 - 3483
(2007/10/03)
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- Synthesis and Structure-Activity Relationships of Acyclic ω Chain Conjugated Diene Analogues of Enisoprost
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A series of acyclic ω chain conjugated diene analogues of enisoprost were synthesized and evaluated for gastric antisecretory and diarrheagenic activities in comparison to enisoprost and a previously identified cyclic dienyl analogue.Several novel approaches to the cuprate reagents involved in the synthesis of the series are described.From this SAR study, it appears that both the conjugated diene and the overall space filling characteristics of the ω chain are important components to the pharmacological profiles and selectivity of these compounds and that a cyclic structure is not required.
- Collins, P. W.,Shone, R. L.,Perkins, W. E.,Gasiecki, A. F.,Kalish, V. J.,et al.
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p. 694 - 704
(2007/10/02)
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- Stereoselective synthesis of (3E,5E)-dien-2-ones and (2E,4E)-dienals via 2-phenylsulfonyl 1,3-dienes
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Michael addition of nitroalkanes to 2-phenylsulfonyl 1,3 dienes proceeded smoothly in the presence of DBU to give nitrosulfones (e.g. 2) in high yield. Transformation of the nitro group of the adduct to a keto function (Nef type reaction) and subsequent elimination of benzenesulfinic acid afforded conjugated dienones and dienals with high stereoselectivity.
- Baeckvall, Jan-E.,Ericsson, Anna M.,Plobeck, Niklas A.,Juntunen, Seppo K.
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p. 131 - 134
(2007/10/02)
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- Polyvinylogation Reagents: 1-Lithio-4-trimethylsiloxy-penta-1,3-diene and 1-Lithio-4-ethoxy-2-methyl-buta-1,3-diene
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Title products, lithiodienol ethers 6a and 7a, synthetic equivalents of 4-lithio pent-3-ene-2-one and 4-lithio-senecialdehyde were obtained by bromine-lithium exchange.They are choice reagents for the transformations 1 -> 2 and 1 -> 3, respectively.
- Duhamel, Lucette,Ancel, Jean-Erick
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p. 9237 - 9250
(2007/10/02)
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- SYNTHESIS WITH MANGANIC SALTS; Part IV1: FREE RADICAL TROST ALLYLATION
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SH2, allylations of various keto compounds with 2-substituted allylic sulfones or sulfides have been efficiently performed using a ternary oxidizing mixture -i.e. manganic acetate, cupric acetate and lead dioxide- in acetic acid.
- Breuilles, P.,Uguen, D.
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p. 357 - 360
(2007/10/02)
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- Synthesis of retinals labelled with 13C in the cyclohexene ring
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In this paper we report the synthesis of five retinals, specifically mono-labelled with 13C at the positions 1,2,3 and 4 and di-labelled with 13 C at the positions 16 and 17, with more than 98percent chemical purity and high 13C incorporation. (1-13C)- and (16,17-13C2) retinal were obtained in 20percent overall yield from (2-13C)- and (1,3-13C2)acetone, (2-13C)- and (3-13C)retinal were prepared in 10percent overall yield from (1-13C)- and (2-13C)acetonitrile, while (4-13C)retinal was synthesized in 17percent overall yield starting from (2-13C)acetonitrile.
- Gebhard, R.,Courtin, J. M. L.,Shadid, J. B.,Haveren, J. van,Haeringen, C. J. van,Lugtenburg, J.
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p. 207 - 214
(2007/10/02)
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- Highly Stereoselective Isomerization of Ynones to Conjugated Dienones Catalyzed by Transition-Metal Complexes
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α,β-Ynones isomerize in the presence of a catalytic amount of IrH5(i-Pr3P)2, RuH2(Ph3P)4-Bu3P, or RuCl2(Ph3P)3-Ph3P in benzene at 35-80 deg C to give (E,E)-α,β:γ,δ-dienones in high yield with high stereoselectivity.This experimentally simple and economica
- Ma, Dawei,Yu, Yihua,Lu, Xiyan
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p. 1105 - 1109
(2007/10/02)
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- Organocuprates Containing Dimethyl Sulfoxide Anion as a Nontransferable Ligand
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Mixed homocuprates and in which the anion of dimethyl sulfoxide acts as a nontransferable ligand are readily prepared from MeSOCH2Li, alkyl- or aryllithium reagents, and Cu(I) salts.These novel cuprates are useful in the conversions of acid chlorides to ketones, conjugate additions to α,β-unsaturated ketones, SN2' reactions with allylic or propargylic acetates and epoxides, and coupling reactions with primary iodides and tosylates.All of these reactions proceed with selective transfer of the ligand R.From the points of view of cost, availability, and lack of interference with product isolation, the Me2SO anion is an ideal nontransferable ligand.
- Johnson, Carl R.,Dhanoa, Daljit S.
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p. 1885 - 1888
(2007/10/02)
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- ISOMERIZATION OF ALLYLIC ALCOHOLS CATALYZED BY VANADIUM OR MOLYBDENUM COMPLEXES.
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Isomerization of primary allylic alcohols proceeds in dichloromethane at 25 degree C in the presence of the catalyst prepared in situ from VO(acac)//2 or MoO//2(acac)//2, and Me//3SiOOSiMe//3 to give tertiary isomers in good yields. The catalysts are also effective for the rearrangements of sec. yields tert. allylic alcohols. The isomerization of an allenyl allylic alcohol, 6-methyl-1,2,5-heptatrien-4-ol, gives either (E)-2-methyl-3,5,6-heptarien-2-ol or (E)-6-methyl-3,5-heptadien-2-one selectively depending on the reaction conditions.
- Matsubara,Okazoe,Oshima,Takai,Nozaki
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p. 844 - 849
(2007/10/02)
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- SOME FEATURES OF THE REARRANGEMENT OF TERTIARY ETHYNYLCARBINOLS IN THE PRESENCE OF POLYVANADIOORGANOSILOXANES
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The rearrangement of various tertiary ethynylcarbinols to α,β-unsaturated aldehydes, catalyzed by polyvanadioorganosiloxanes, was studied, and the activation parameters of the reaction were determined.The structures of the side products were established, and proposals were made about the mechanism of their formation.Additives which suppress the side reactions were found.As a result the yields of the unsaturated aldehydes were increased significantly.
- Erman, M. B.,Aul'chenko, I. S.,Kheifits, L. A.
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- Production of α,β-unsaturated ketones
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A process for the production of α,β-unsaturated ketones by reaction of an aldehyde with a ketone in the presence of a catalyst consisting essentially of zinc oxide in the liquid phase. The ketones obtained are suitable in some cases as solvents and in some cases as intermediates for the production of valuable odorants, dyes, plastics and especially natural substances.
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