31739-46-5Relevant academic research and scientific papers
Controlled Cyclopolymerization of 1,5-Hexadiynes to Give Narrow Band Gap Conjugated Polyacetylenes Containing Highly Strained Cyclobutenes
Kang, Cheol,Jung, Kijung,Ahn, Sojeong,Choi, Tae-Lim
, p. 17140 - 17146 (2020)
For decades, cyclopolymerization of α,ω-diyne derivatives has been an effective method to synthesize various soluble polyacetylenes containing five- to seven-membered rings in the backbone. However, cyclopolymerization to form four-membered carbocycles was considered impossible due to their exceptionally high ring strain (～30 kcal/mol). Herein, we demonstrate the successful cyclopolymerization of rationally designed 1,5-hexadiyne derivatives to afford various polyacetylenes containing highly strained cyclobutenes in each repeat unit. After screening, Ru catalysts containing bulky diisopropylphenyl groups promoted challenging four-membered ring cyclization efficiently from various monomers, enabling the synthesis of high molecular weight (up to 40 kDa) polyacetylenes in a controlled manner. Furthermore, living polymerization allowed for block copolymer synthesis by combining with ring-opening metathesis polymerization as well as block copolymerization of two different 1,5-hexadiyne monomers to give a fully conjugated polyacetylene. These new polymers unexpectedly showed much narrower band gaps than conventional substituted polyacetylenes by >0.2 eV. Interestingly, computational studies showed much smaller bond length alternation in the conjugated backbone containing cyclobutenes, resulting in highly delocalized πelectrons along the polymer chain and lower band gaps.
Laccase-mediated Oxidations of Propargylic Alcohols. Application in the Deracemization of 1-arylprop-2-yn-1-ols in Combination with Alcohol Dehydrogenases
González-Granda, Sergio,Méndez-Sánchez, Daniel,Lavandera, Iván,Gotor-Fernández, Vicente
, p. 520 - 527 (2019/11/16)
The catalytic system composed by the laccase from Trametes versicolor and the oxy-radical TEMPO has been successfully applied in the sustainable oxidation of fourteen propargylic alcohols. The corresponding propargylic ketones were obtained in most cases in quantitative conversions (87–>99 % yield), demonstrating the efficiency of the chemoenzymatic methodology in comparison with traditional chemical oxidants, which usually lead to problems associated with the formation of by-products. Also, the stereoselective reduction of propargylic ketones was studied using alcohol dehydrogenases such as the one from Ralstonia species overexpressed in E. coli or the commercially available evo-1.1.200, allowing the access to both alcohol enantiomers mostly with complete conversions and variable selectivities depending on the aromatic pattern substitution (97–>99 % ee). To demonstrate the compatibility of the laccase-mediated oxidation and the alcohol dehydrogenase-catalyzed bioreduction, a deracemization strategy starting from the racemic compounds was developed through a sequential one-pot two-step process, obtaining a selection of (S)- or (R)-1-arylprop-2-yn-1-ols with excellent yields (>98 %) and selectivities (>98 % ee) depending on the alcohol dehydrogenase employed.
A novel synthesis of N-hydroxy-3-aroylindoles and 3-aroylindoles
Ieronimo, Gabriella,Palmisano, Giovanni,Maspero, Angelo,Marzorati, Alessandro,Scapinello, Luca,Masciocchi, Norberto,Cravotto, Giancarlo,Barge, Alessandro,Simonetti, Marco,Ameta, Keshav Lalit,Nicholas, Kenneth M.,Penoni, Andrea
supporting information, p. 6853 - 6859 (2018/10/20)
A straightforward indole synthesis via annulation of C-nitrosoaromatics with conjugated terminal alkynones was realised achieving a simple, highly regioselective, atom- and step economical access to 3-aroylindoles in moderate to good yields. Further functionalizations of indole scaffolds were investigated and an easy way to JWH-018, a synthetic cannabinoid, was achieved.
A general synthesis of ynones from aldehydes via oxidative C-C bond cleavage under aerobic conditions
Wang, Zhaofeng,Li, Li,Huang, Yong
supporting information, p. 12233 - 12236 (2014/10/15)
We describe a direct synthesis of various ynones from readily available aldehydes and hypervalent alkynyl iodides. In this method, a gold catalyst and a secondary amine work synergistically to produce the trisubstituted allenyl aldehyde, which can be conv
N-Vinylpyridinium tetrafluoroborate salts as reagents for the stereoselective and regioselective synthesis of symmetrical (2E,4E)-1,6-dioxo-2,4-dienes
Gao, Ge,Brown, Neil,Minatoya, Machiko,Buszek, Keith R.
scheme or table, p. 6491 - 6494 (2009/04/06)
We had previously demonstrated the utility of N-vinylpyridinium tetrafluoroborate salts as novel electrophilic coupling partners in Pd(0)-catalyzed Suzuki cross-coupling reactions with aryl and vinyl boronic acids. We now report that these crystalline, air-stable, and non-hygroscopic salts are also useful reagents for the synthesis of symmetrical (2E,4E)-1,6-dioxo-2,4-dienes (diene diones), which in turn are valuable starting materials for the synthesis of various five-membered heterocycles. The optimization of reaction conditions and the scope and limitations of the reductive dimerization are discussed.
