18913-31-0Relevant academic research and scientific papers
RAFT polymerization of a novel allene-derived asymmetrical divinyl monomer: A facile strategy to alkene-functionalized hyperbranched vinyl polymers with high degrees of branching
Bao, Youmei,Shen, Guorong,Liu, Xiaohui,Li, Yuesheng
, p. 2959 - 2969 (2013)
Hyperbranched vinyl polymers with high degrees of branching (DBs) up to 0.43 functionalized with numerous pendent allene groups have been successfully prepared via reversible addition fragmentation chain transfer polymerization of a state-of-art allene-derived asymmetrical divinyl monomer, allenemethyl methacrylate (AMMA). The gelation did not occur until high monomer conversions (above 90%), as a result of the optimized reactivity difference between the two vinyl groups in AMMA. The branched structure was confirmed by a combination of a triple-detection size exclusion chromatography (light scattering, refractive index, and viscosity detectors) and detailed 1H NMR analyses. A two-step mechanism is proposed for the evolution of branching according to the dependence of molecular weight and DB on monomer conversion. Controlled radical polymerization proceeds until moderate conversions, mainly producing linear polymers. Subsequent initiation and propagation on the polymerizable allene side chains as well as the coupling of macromolecular chains generate numerous branches at moderate-to-high monomer conversions, dramatically increasing the molecular weight of the polymer. AMMA was also explored as a new branching agent to construct poly(methyl methacrylate)-type hyperbranched polymers by its copolymerization with methyl methacrylate. The DB can be effectively tuned by the amount of AMMA, showing a linear increase trend. The pendent allene groups in the side chains of the copolymers were further functionalized by epoxidation and thiol-ene chemistry in satisfactory yields.
Synthesis and Characterization of Cyanobutadiene Isomers-Molecules of Astrochemical Significance
Esselman, Brian J.,Hyland, Grace E.,Knezz, Stephanie N.,Kougias, Samuel M.,Lee, Daniel J.,McMahon, Robert J.,Owen, Andrew N.,Patel, Aatmik R.,Sanchez, Rodrigo A.,Woods, R. Claude
, (2020/05/05)
Four cyanobutadiene isomers of considerable interest to the organic chemistry, molecular spectroscopy, and astrochemistry communities were synthesized in good yields and isolated as pure compounds: (E)-1-cyano-1,3-butadiene (E-1), (Z)-1-cyano-1,3-butadiene (Z-1), 4-cyano-1,2-butadiene (2), and 2-cyano-1,3-butadiene (3). A diastereoselective synthesis was developed to generate (E)-1-cyano-1,3-butadiene (1) (10:1 E/Z) via tandem SN2 and E2′ reactions. The potential energy surfaces of the E2′ reactions leading to (E)- A nd (Z)-1-cyano-1,3-butadiene (1) were analyzed by density functional theory calculations, and the observed diastereoselectivity was rationalized in the context of the Curtin-Hammett principle. The preparation of pure samples of these reactive compounds enables measurement of their laboratory rotational spectra, which are the critical data needed to search for these species in space by radioastronomy.
Dearomative Cycloadditions Utilizing an Organic Photosensitizer: An Alternative to Iridium Catalysis
Rolka, Alessa B.,Koenig, Burkhard
supporting information, p. 5035 - 5040 (2020/07/15)
A highly efficient, cheap, and organic alternative to the commonly used iridium photosensitizer (Ir[dF(CF3)ppy]2(dtbpy))PF6 ([Ir-F]) is presented for visible-light energy transfer catalysis. The organic dye 2CzPN surpasses [Ir-F] in selectivity while at t
Formation of 6-Azaindoles by Intramolecular Diels-Alder Reaction of Oxazoles and Total Synthesis of Marinoquinoline A
Jhaveri, Dishit P.,Osano, Mana,Wipf, Peter
supporting information, p. 2215 - 2219 (2020/04/09)
A new variant of the intramolecular Diels-Alder oxazole (IMDAO) cycloaddition that provides direct access to 6-azaindoles was developed. The IMDAO reaction was applied in a total synthesis of the aminophenylpyrrole-derived alkaloid marinoquinoline A, also
Cobalt-Catalyzed C8-Dienylation of Quinoline-N-Oxides
Khan, Salman,Nair, Akshay M.,Shukla, Rahul K.,Volla, Chandra M. R.
supporting information, p. 17042 - 17048 (2020/08/05)
An efficient Cp*CoIII-catalyzed C8-dienylation of quinoline-N-oxides was achieved by employing allenes bearing leaving groups at the α-position as the dienylating agents. The reaction proceeds by CoIII-catalyzed C?H activation of qui
Rhodium-Catalyzed Enantioselective Cyclization of 3-Allenyl-indoles: Access to Functionalized Tetrahydrocarbazoles
Grugel, Christian P.,Breit, Bernhard
supporting information, p. 5798 - 5802 (2019/06/08)
A highly selective rhodium-catalyzed cyclization of tethered 3-allenylindoles is reported. In a smooth reaction, 1-vinyltetrahydrocarbazoles are obtained in excellent yields and enantioselectivities. Aside from a great functional group tolerance, this method requires neither the Schlenk technique nor the use of anhydrous solvents. Preliminary mechanistic investigations proved that the reaction proceeds via an intermediary formed spiroindolenine which rapidly undergoes an acid-catalyzed stereospecific migration.
Rhodium-Catalyzed Diastereo- And Enantioselective Tandem Spirocyclization/Reduction of 3-Allenylindoles: Access to Functionalized Vinylic Spiroindolines
Grugel, Christian P.,Breit, Bernhard
supporting information, p. 9672 - 9676 (2019/12/24)
A highly selective rhodium-catalyzed tandem spirocyclization/reduction of 3-allenylindoles is reported. By employing a Hantzsch ester as reductant, vinylic spiroindolines are obtained in excellent yields as well as diastereo- and enantioselectivity. In addition, the reaction's synthetic utility is highlighted by broad functional group compatibility and exemplified by a gram scale reaction with subsequent assorted transformations.
Selective Cascade Reaction of Bisallenes via Palladium-Catalyzed Aerobic Oxidative Carbocyclization–Borylation and Aldehyde Trapping
Naidu, Veluru Ramesh,Posevins, Daniels,Volla, Chandra M. R.,B?ckvall, Jan-E.
supporting information, p. 1590 - 1594 (2017/02/05)
A cascade reaction, consisting of a palladium-catalyzed regioselective aerobic oxidative carbocyclization–borylation of bisallenes and a final aldehyde trapping, afforded triene alcohols with high diastereoselectivity. The cascade reaction occurs under mild reaction conditions and proceeds via an allylboron intermediate that is trapped by the aldehyde in a stereoselective manner.
Synthesis of Functionalized [3], [4], [5] and [6]Dendralenes through Palladium-Catalyzed Cross-Couplings of Substituted Allenoates
Lippincott, Daniel J.,Linstadt, Roscoe T. H.,Maser, Michael R.,Lipshutz, Bruce H.
supporting information, p. 847 - 850 (2017/01/14)
A mild method for the synthesis of highly functionalized [3]–[6]dendralenes is reported, representing a general strategy to diversely substituted higher homologues of the dendralenes. The methodology utilizes allenoates bearing various substitution patter
Gold-catalyzed N, O-functionalizations of 6-allenyl-1-ynes with n-hydroxyanilines to construct benzo[b]-azepin-4-one cores
Raj, Antony Sekar Kulandai,Kale, Balaji S.,Mokar, Bhanudas Dattatray,Liu, Rai-Shung
supporting information, p. 5340 - 5343 (2017/11/07)
Gold-catalyzed reactions of 6-allen-1-ynes with N-hydroxyanilines afford thermally stable benzoazepin-4-ones in anti-selectivity; these anti-configured products are easily isomerized to their syn-isomers on a silica column. The mechanism of reactions likely involve initial nitrone/allene cycloadditions, followed by skeletal rearrangement of resulting intermediates.
