30625-91-3Relevant academic research and scientific papers
Metal-catalyzed formation of 1,3-cyclohexadienes: A catalyst-dependent reaction
Zhu, Shifa,Huang, Xiaobing,Zhao, Tian-Qi,Ma, Tongmei,Jiang, Huanfeng
, p. 1225 - 1233 (2015)
A metal-dependent and complementary catalytic method to synthesize the cyclohexadienes has been developed. When gold or indium salts were used as catalysts, 1,3-cyclohexadiene (1,3-CHD) could be obtained; when Cu(OTf)2 was used as the catalyst,
Chemoselective Biohydrogenation of Alkenes in the Presence of Alkynes for the Homologation of 2-Alkynals/3-Alkyn-2-ones into 4-Alkynals/Alkynols
Colombo, Danilo,Brenna, Elisabetta,Gatti, Francesco G.,Ghezzi, Maria Chiara,Monti, Daniela,Parmeggiani, Fabio,Tentori, Francesca
, p. 2638 - 2648 (2019/05/16)
The chemoselective hydrogenation of alkenes in the presence of alkynes is a very challenging transformation to achieve with traditional chemical methods. The development of an effective procedure to perform this transformation would enrich the tool-kit available to organic chemists for the development of useful synthetic routes, and the creation of novel structural motifs. The reduction of activated alkene bonds by ene-reductases (ERs) is completely chemoselective, because of the mechanism of the reaction. Thus, we investigated the use of ERs belonging to the Old Yellow Enzyme family for the reduction of α,β-unsaturated aldehydes with a conjugated C≡C triple bond at the γ position. This reaction was exploited as the key step for the development of an effective homologation route to convert aryl and alkyl substituted propynals and butynones into 4-alkynals and 4-alkynols, avoiding some troublesome or hazardous steps of known synthetic routes. (Figure presented.).
Base-mediated decomposition of amide-substituted furfuryl tosylhydrazones: Synthesis and cytotoxic activities of enynyl-ketoamides
Ji, Fanghua,Peng, Hui,Zhang, Xiaoting,Lu, Wenhua,Liu, Shubin,Jiang, Huanfeng,Liu, Bo,Yin, Biaolin
, p. 2092 - 2102 (2015/04/21)
Base-mediated decomposition of amide-substituted furfuryl tosylhydrazones afforded practical access to novel multifunctionalized enynyl-ketoamides. In addition, furfuryl tosylhydrazones with stable furan rings underwent an interesting tosyl-group migratio
Regioselective cis,vic-dihydroxylation of α,β,γ,δ- unsaturated carboxylic esters: Enhanced γ,δ-selectivity by employing trifluoroethyl or hexafluoroisopropyl esters
Schmidt-Leithoff, Joachim,Brückner, Reinhard
, p. 2641 - 2645 (2008/09/16)
The regioselectivity of Sharpless asymmetric dihydroxylation (AD) of α,β,γ,δ-unsaturated carboxylic esters was studied as a function of α-, β-, and δ-substituents and for fluorine-free versus fluorinated esters. The latter showed increased or complete γ,δ-selectivities: the hexafluoroisopropyl ester being superior to the trifluoroethyl ester. Olefinations of α,β-unsaturated aldehydes with phosphorus ylide 36 or phosphonate anion 41 provided α,β, γ,δ-unsaturated trifluoroethyl esters, leading inter alia to complete trans selectivity and to 31 with 94% E selectivity, respectively. Georg Thieme Verlag Stuttgart.
Two carbon homologated α,β-unsaturated aldehydes from alcohols using the in situ oxidation-Wittig reaction
Reid, Mark,Rowe, David J.,Taylor, Richard J. K.
, p. 2284 - 2285 (2007/10/03)
The in situ oxidation-Wittig reaction, followed by subsequent hydrolysis, has been applied to the conversion of primary alcohols into α,β -unsaturated aldehydes. This conversion, which proceeds via the intermediacy of the homologated unsaturated dioxolanes, gives good to excellent yields with a range of benzylic alcohols and heterocyclic methanols.
Oxovanadium complex-catalyzed aerobic oxidation of propargylic alcohols
Maeda, Yasunari,Kakiuchi, Nobuyuki,Matsumura, Satoshi,Nishimura, Takahiro,Kawamura, Takashi,Uemura, Sakae
, p. 6718 - 6724 (2007/10/03)
A catalytic system consisting of vanadium oxyacetylacetonate [VO(acac)2] and 3 A molecular sieves (MS3A) in acetonitrile works effectively for the aerobic oxidation of propargylic alcohols [R1CH-(OH)C≡CR2] to the corresponding carbonyl compounds under an atmospheric pressure of molecular oxygen. Although the reactivity of α-acetylenic alkanols (R1 = alkyl) is lower compared to that of the alcohols of R1 = aryl, alkenyl, and alkynyl, the use of VO(hfac)2 as a catalyst and the addition of hexafluoroacetylacetone improve the product yield in these cases. A catalytic cycle involving a vanadium(V) alcoholate species and β-hydrogen elimination from it has been proposed for this oxidation.
Regio- and stereoselective synthesis of vinylallenes by 1,5-(S(N)'')- substitution of enyne acetates and oxiranes with organocuprates
Purpura, Martin,Krause, Norbert
, p. 267 - 275 (2007/10/03)
Enyne acetates 2, 4, 6, and 8, as well as enyne oxiranes 10, with different substitution patterns react with organocuprates regioselectively under 1,5-(S(N)2'')-substitution to provide vinylallenes 11 and 12. With lithium dimethylcuprate, reduced vinylallenes originating from a [formal) transfer of a hydride ion to the substrate are formed in some cases. The products are usually obtained as mixtures of (E/Z)-isomers; however, pure (E)-vinylallenes are formed occasionally. The 1,5-substitutions can also be carried out with catalytic amounts of copper reagents. The reaction of chiral enyne acetate (S)-2a with tBu2CuLi · LiCN proceeds enantioselectively, so that this transformation constitutes a new case of remote stereocontrol.
Synthesis of polyphenylene derivatives by thermolysis of enediynes and dialkynylaromatic monomers
John, Jens A.,Tour, James M.
, p. 15515 - 15534 (2007/10/03)
Described are the syntheses of substituted enediynes and dialkynylaromatics using Pd- or Pd/Cu-catalyzed cross coupling procedures. The products were then thermalized to afford the corresponding poly(p- phenylene)s, poly(1,4-naphthalene)s, poly(benzo[c]thiophene)s, and poly(dibenzothiophene)s. Fifteen examples are provided that show the scope of the polymerization process based upon substituent patterns and cyclization moieties. The superb thermal resiliency of the newly derived polymers is demonstrated using thermogravimetric analysis. The polymer structure was generally confirmed using IR data correlations to small molecules that resembled the polymers' repeat unit structure. Radical trapping of dimeric intermediates, that were analyzed by GCMS, further substantiated the proposed mechanistic route. The step-growth polymerization pattern was determined by monitoring the degree of monomer consumption versus the polymer molecular weight.
Reactions of Carbenes with Oxetane and with Oxetane/ Methanol Mixtures
Kirmse, Wolfgang,Lelgemann, Rudolf,Friedrich, Klaus
, p. 1853 - 1863 (2007/10/02)
Ethoxycarbonylcarbene, bis(methoxycarbonyl)carbene, phenylcarbene (17a), diphenylcarbene (17b), fluorenylidene (17c), 2-furylcarbene (31a), 2-furyl(phenyl)carbene (31b), 4-oxo-2,5-cyclohexadienylidene (40), and 4,4-dimethyl-2,5-cyclohexadienylidene (53) were generated by photolysis of the appropriate diazo compounds.With neat oxetane, most of these carbenes react by competitive C-H insertion (B -> A, Scheme 1) and ylide formation (B -> C). 31a and 40 do not insert into C-H bonds; 31b does not attack oxetane but rearranges exclusively with formation of 26.The ylides undergo Stevens rearrangement to give tetrahydrofurans (C -> D) and α',β-elimination, leading to allyl ethers (C -> E).With oxetane/ methanol mixtures, the intervention of oxonium ions (H) is indicated by the formation of 1,3-dialkoxypropanes (I).The oxonium ions arise either by protonation of the ylides (C -> H) or by protonation of the carbenes (B -> G), followed by electrophilic attack of the carbocations (G) at oxetane (G -> H).The former route is followed by the alkoxycarbonylcarbenes and by 40; the ylides derived from the remaining carbenes do not react with methanol, owing to their rapid Stevens rearrangements.Protonation of the carbenes 17b, 31, and 53 is clearly indicated by their product ratios and, for 31, by the formation of isomeric ethers (33, 36).The more electrophilic carbenes discriminate but slightly between oxetane and methanol while the more nucleophilic carbenes (17b, 31, 53) prefer the protic methanol strongly over the aprotic oxetane. Key Words: Carbenes/ Oxygen ylides/ Stevens rearrangement/ Oxonium ions/ Insertion, O-H/ Ylides
