109-50-2Relevant academic research and scientific papers
(Z)-3-alkylidene-4,5-dihydro-4-hydroxy-5-methyl-2-(3H)-furanones by regio- and diastereoselective ene reaction of singlet oxygen (Schenk reaction) with γ-hydroxy vinylstannanes: An enantioselective synthesis of dihydromahubanolide B
Adam,Klug
, p. 567 - 572 (1994)
(Z)-3-Alkylidene-4,5-dihydro-4-hydroxy-5-methyl-2-(3H)-furanones 5 were prepared from appropriately substituted propargylic alcohols 1 by a sequence of hydromagnesation to γ-hydroxy vinylstannanes 2, subsequent photooxygenation and reduction to stannyl diols 3, iododestannylation to iodo diols 4, and finally cyclization by palladium-catalyzed carbonylation (for 5a) or Ni(CO)2(PPh3)2 (for 5b,c). The reaction sequence can be performed enantioselectively by starting with chiral propargylic alcohols. The current approach constitutes a convenient four-step synthesis of optically active lactones 5 from readily available starting materials and is applied herein to the preparation of the natural lactone dihydromahubanolide B.
Phosphine-Catalyzed Intermolecular Annulations of Fluorinated ortho-Aminophenones with Alkynones – The Switchable [4+2] or [4+2]/[3+2] Cycloaddition
Zhang, Yanshun,Sun, Yaoliang,Wei, Yin,Shi, Min
supporting information, p. 2129 - 2135 (2019/03/13)
A phosphine-catalyzed intermolecular annulation reaction of functionalized ortho-aminoacetophenones with alkynones has been disclosed in this paper. A variety of 2-alkynylquinolines and benzo-fused indolizine were selectively afforded in moderate to good yields at different reaction temperatures and with different phosphine catalysts via the in situ generated zwitterionic intermediate derived from alkynone and phosphine. (Figure presented.).
Synthesis of Vinyl-, Allyl-, and 2-Boryl Allylboronates via a Highly Selective Copper-Catalyzed Borylation of Propargylic Alcohols
Mao, Lujia,Bertermann, Rüdiger,Emmert, Katharina,Szabó, Kálmán J.,Marder, Todd B.
supporting information, p. 6586 - 6589 (2017/12/26)
An efficient methodology for the synthesis of vinyl-, allyl-, and (E)-2-boryl allylboronates from propargylic alcohols via Cu-catalyzed borylation under mild conditions is reported. In the presence of commercially available Cu(OAc)2 or Cu(acac)2 and Xantphos, the reaction affords the desired products in up to 92% yield with a broad substrate scope (43 examples). Isolation of an allenyl boronate as the reaction intermediate suggests that an insertion-elimination-type reaction, followed by borylcupration, is involved in the borylation of propargylic alcohols.
In situ generation of nucleophilic allenes by the gold-catalyzed rearrangement of propargylic esters for the highly diastereoselective formation of intermolecular C(sp3)-C(sp2) bonds
Yu, Yang,Yang, Weibo,Rominger, Frank,Hashmi, A. Stephen K.
supporting information, p. 7586 - 7589 (2013/07/26)
New perspectives, in particular for the synthesis of isochromane derivatives (see scheme), are provided by the title reaction. Excellent diastereoselectivites are achieved in this reaction which proceeds through a gold-catalyzed 1,3-acyloxy migration. In some cases exclusively the Z isomer is detected. Copyright
The substrate spectrum of the inverting sec-alkylsulfatase Pisa1
Schober, Markus,Knaus, Tanja,Toesch, Michael,MacHeroux, Peter,Wagner, Ulrike,Faber, Kurt
, p. 1737 - 1742 (2012/07/31)
The substrate spectrum of the inverting alkylsulfatase Pisa1 was investigated using a range of sec-alkyl sulfate esters bearing aromatic, olefinic and acetylenic moieties. Perfect enantioselectivities were obtained for substrates bearing groups of different size adjacent to the sulfate ester moiety. Insufficient selectivities could be doubled by using dimethyl sulfoxide (DMSO) as co-solvent. Hydrolytically unstable benzylic sulfate esters could be sufficiently stabilised by introduction of electron-withdrawing substituents. Overall, Pisa1 appears to be a very useful inverting alkylsulfatase for the deracemisation of rac-sec-alcohols via enzymatic hydrolysis of their corresponding sulfate esters, which furnishes homochiral products possessing the 'anti-Kazlauskas' configuration. Copyright
Synthesis of novel 2H,5H-dihydrofuran-3-yl ketones via ISNC reactions
Grandbois, Matthew L.,Betsch, Kelsie J.,Buchanan, William D.,Duffy-Matzner, Jetty L.
supporting information; scheme or table, p. 6446 - 6449 (2011/02/23)
Unique 1-[2H,5H-dihydrofur-3-yl]ketones have been synthesized from propargylic nitroethers via intramolecular cycloadditions involving silyl nitronates. Various substituent groups were placed on the 2 and 5 positions of the dihydrofuran rings. We examined the scope of the long-range coupling in proton NMR of the oxo-dihydrofuran products. The identities of the diastereomers resulting from the Michael addition/cycloaddition reactions were tentatively assigned for the first time. CAChe MNDO PM5 and CONFLEX programs were engaged to assist with the identification of these stereoisomers. The reaction times and conditions for these oxo-dihydrofurans were found to be different than that of the published dihydrofuranals, which led us to propose a different mechanism.
Nickel-catalyzed asymmetric cross-couplings of racemic propargylic halides with arylzinc reagents
Smith, Sean W.,Fu, Gregory C.
supporting information; experimental part, p. 12645 - 12647 (2009/05/09)
A stereoconvergent method for the catalytic asymmetric Negishi cross-coupling of racemic secondary propargylic halides with arylzinc reagents has been developed. Neither family of compounds has previously been shown to be a suitable partner in such coupling processes. From a practical point of view, it is noteworthy that the catalyst components (NiCl2·glyme and pybox ligand 1) are commercially available. Copyright
Adducts of thianthrene- and phenoxathiin cation radical salts with symmetrical alkynes. Structure and formation of cumulenes on alumina leading to α-diketones, α-hydroxyalkynes, and α-acetamidoalkynes
Shine, Henry J.,Rangappa, Paramashivappa,Marx, John N.,Shelly, Dennis C.,Ould-Ely, Teyeb,Whitmire, Kenton H.
, p. 3877 - 3883 (2007/10/03)
Thianthrene cation radical tetrafluoroborate (Th.+BF 4-) added to 2-butyne, 3-hexyne, 4-octyne, and 5-decyne in MeCN to form trans bisadducts E(Th+)C=C(Th+)R, where E = Me, Et, Pr, Bu (7a-d). Phenoxathiin cation radical tetrafluoroborate (PO .+BF4-) added similarly to the last three alkynes to form adducts E(PO+)C=C(PO+)E, 8b-d. Cyclic monoadducts were not found. The trans structures of 7 and 8 were deduced with X-ray crystallography (7c) and NME spectroscopy. When solutions of adducts in CHCl3 and MeCN were deposited on activated alumina, elimination of thianthrene (Th) and phenoxathiin (PO) occurred almost quantitatively. Detailed studies with (7b-d) indicated that a cumulene (15) was formed by the elimination of Th and that 15 was subsequently converted into small amounts of other products. In CHCl3, these products were the respective alkyne, thianthrene 5-oxide, an α-diketone (11), an α-hydroxyalkyne (12), and hydrogen. The same products were formed in MeCN along with an α-acetamidoalkyne (13). The formation of 15 and products derived from it is explained and was confirmed by preparation and reactions of 2,3,4-hexatriene.
The effect of catechin derivatives on the enantioselectivity of lipase-catalyzed hydrolyses of alkynol benzoate esters
Nakamura, Kaoru,Takenaka, Keishi
, p. 415 - 422 (2007/10/03)
Polyphenols, such as (+)-catechin and pyrogallol could be used to enhance stereochemical control in the lipase-catalyzed hydrolysis of alkynol benzoate esters, leading to increased enantioselectivities in the kinetic resolution of alkynols with lipase Amano AH.
Enantioselective reduction of prochiral ketones by catecholborane catalysed by chiral group 13 complexes
Blake, Alexander J.,Cunningham, Anthony,Ford, Alan,Teat, Simon J.,Woodward, Simon
, p. 3586 - 3594 (2007/10/03)
LiGaH4, in combination with the S,O-chelate 2-hydroxy-2′-mercapto-1,1′-binaphthyl (MTBH2), forms an active catalyst for the asymmetric reduction of prochiral ketones, with catecholborane as the hydride source. Enantioface differentiation is on the basis of the steric requirements of the ketone substituents. Aryl/ n-alkyl ketones are reduced in 90-93% ee and RC(O)Me (e.g. R = iPr, cycloC6H11, tBu) in 60-72% ee. Other borane sources and alternative catalyst structures based on indium do not form enantioselective catalysts.
