30319-05-2Relevant academic research and scientific papers
Cope Rearrangement in the Thiophene Series
MacDowell, Denis W. H.,Purpura, Joseph M.
, p. 183 - 188 (1986)
The inability to observe Cope rearrangement at elevated temperature for diethyl α-allylphenylmalonate does not extend to the analogous systems resulting from replacement of the benzene ring by 2- and 3-thiophene nuclei.Thermal rearrangement of diethyl α-allyl-2-thienylmalonate (5) at 250-260 deg C for 12 h produces the expected Cope rearrangement product diethyl (3-allyl-2-thienyl)malonate (6) (49percent) accompanied by ethyl 6-carboethoxy-5,6-dihydro-4H-5-cyclopentathiopheneacetate (7) (28percent).The structural verification of 6 was obtained by degradation to 3-allyl-2-methylthiophene which was compared with an authentic sample obtained by synthesis.The structure of 7 was based on analogy.Similar results were observed with the 3-substituted analogues of 5, both diethyl (2-allyl-3-thienyl)malonate (14) and ethyl 4-carboethoxy-5,6-dihydro-4H-5-cyclopentathiopheneacetate (15) being formed.In this case the structure of 14 was verified by synthesis.Speculative mechanistic considerations are offered regarding the mode of transformation of 6 to 7 and 14 to 15.That the methine proton of the malonate substituent in 6 and 14 is involved in this transformation is seen by the inability of the appropriate methyl-substituted derivative of 6 to undergo thermal cyclization.
Synthesis, X-ray crystallographic analysis, and theoretical structure analysis of tetrathienylethenes designed for photo- and electrochromism
Ikeda, Hiroshi,Sakai, Azusa,Namai, Hayato,Kawabe, Akinori,Mizuno, Kazuhiko
, p. 8338 - 8342 (2007)
As part of an effort to develop a new chromic system that responds to both photoexcitation and electron transfer, tetrakis(2-methylthien-3-yl)ethene (3a) and its tetrakismethylthio derivative (3b) were synthesized. The results of X-ray crystallographic and theoretical analyses of these substances suggest that (1) conformers of 3 with an antiparallel arrangement of two vicinal thienyl groups will undergo photocyclization, and (2) the most stable conformer of 3 having an anti-double parallel conformation will not. These predictions were preliminarily confirmed by the results of photochemical and cyclic voltammetry studies.
Remarkably Efficient Iridium Catalysts for Directed C(sp2)-H and C(sp3)-H Borylation of Diverse Classes of Substrates
Chattopadhyay, Buddhadeb,Hassan, Mirja Md Mahamudul,Hoque, Md Emdadul
supporting information, p. 5022 - 5037 (2021/05/04)
Here we describe the discovery of a new class of C-H borylation catalysts and their use for regioselective C-H borylation of aromatic, heteroaromatic, and aliphatic systems. The new catalysts have Ir-C(thienyl) or Ir-C(furyl) anionic ligands instead of the diamine-type neutral chelating ligands used in the standard C-H borylation conditions. It is reported that the employment of these newly discovered catalysts show excellent reactivity and ortho-selectivity for diverse classes of aromatic substrates with high isolated yields. Moreover, the catalysts proved to be efficient for a wide number of aliphatic substrates for selective C(sp3)-H bond borylations. Heterocyclic molecules are selectively borylated using the inherently elevated reactivity of the C-H bonds. A number of late-stage C-H functionalization have been described using the same catalysts. Furthermore, we show that one of the catalysts could be used even in open air for the C(sp2)-H and C(sp3)-H borylations enabling the method more general. Preliminary mechanistic studies suggest that the active catalytic intermediate is the Ir(bis)boryl complex, and the attached ligand acts as bidentate ligand. Collectively, this study underlines the discovery of new class of C-H borylation catalysts that should find wide application in the context of C-H functionalization chemistry.
Mild-Base-Promoted Arylation of (Hetero)Arenes with Anilines
Monzón, Diego M.,Santos, Tanausú,Pinacho-Crisóstomo,Martín, Víctor S.,Carrillo, Romen
, p. 325 - 333 (2018/01/15)
Transition metal-free radical arylation of heteroarenes is achieved at room temperature by simply adding aqueous sodium carbonate to a solution of the corresponding heteroarene and arenediazonium salt, which can even be formed in situ. Such an easy, inexpensive and mild methodology has been optimized and applied to the expeditious modification of interesting molecular cores like naphthylimide or bisthienylcyclopentenes.
Practical preparation of ethyl 2-methylthiophene-3-carboxylate
Kogami, Masakazu,Watanabe, Nobuhide
experimental part, p. 797 - 798 (2011/07/29)
A safe and efficient process for the preparation of ethyl 2-methylthiophene-3-carboxylate (5) was devised. This process provides several advantages over the precedents, involving operational simplicity, avoidance of the use of strong bases such as n-butyllithium and application of noncryogenic conditions, and enabled to prepare 5 in 52% overall yield from commercially available 2-methylthiophene on a multikilogram scale.
PROCESS FOR THE PRODUCTION OF INTERMADIATES FOR THE PREPARATION OF TRICYCLIC BENZIMIDAZOLES
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Page/Page column 99, (2010/11/25)
The invention relates to a process for the synthesis of compounds of the formula 1-a and compounds of the formula 1-b. The compounds of the formula 1-a and the compounds of the formula 1-b, in which the substituents R1, R2, R3, and Ar have the meanings indicated in the description, are valuable intermediates for the preparation of pharmaceutically active compounds.
Polycyclic fused heteroring compounds metal complexes and polymerization process
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Page 16, (2010/02/10)
Metal complexes comprising a polycyclic, heteroatom containing fused ring compound comprising at least a cyclopentadienyl ring having fused thereto a 5-membered polyatomic ring containing one or more ring atoms selected from groups 15 or 16 of the Periodic Table of the Elements and lacking substituents forming 6-membered, aromatic fused rings; polymerization catalysts; and olefin polymerization processes using the same are disclosed.
Bistable photoswitching in the film of fluorescent photochromic polymer: Enhanced fluorescence emission and its high contrast switching
Lim, Seon-Jeong,An, Byeong-Kwan,Park, Soo Young
, p. 6236 - 6239 (2008/02/02)
The synthesis of aggregation-induced enhanced emission (AIEE)-based fluoroscent photochromic polymer, poly(DCS-BTE), whose strong fluorescence in the neat polymer film could photoswitched, was discussed. Polymeric film consisting of DCS in PMMA matrix were fabricated by spin-coating. Molecular planarization and J-type aggregation were observed in the DCS molecules gated by the specific intermolecular interactions in the solid state. The results show that the erasable fluorescence photoimaging on the spin-coated poly(DCS-BTE) film is successfully demonstrated.
Photoswitchable organic nanoparticles and a polymer film employing multifunctional molecules with enhanced fluorescence emission and bistable photochromism
Lim, Seon-Jeong,An, Byeong-Kwan,Sang, Don Jung,Chung, Myung-Ae,Soo, Young Park
, p. 6346 - 6350 (2007/10/03)
Get turned on: Fluorescent photochromic organic nanoparticles (FPONs) of 1 (see picture) show a strongly enhanced fluorescence emission with increasing concentration and bistable photochromism. High-contrast on/off fluorescence switching has been successfully implemented in size-tuned FPONs of 1 and also in a photo-rewritable polymer film highly loaded with 1. (Chemical equation presented).
Metallocene compounds, process for their preparation and their use in catalytic systems for the polymerization of olefins
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, (2008/06/13)
A class of metallocene compounds is disclosed having general formula (I) wherein Y is a moiety of formula (II) wherein A, B, and D, same or different from each other, are selected from an element of the groups 14 to 16 of the Periodic Table of the Elements (new IUPAC version), with the exclusion of nitrogen and oxygen; R1, R2, R3, R4and R5are hydrogen or hydrocarbon groups, Z is selected from a moiety of formula (II) as described above and from a moiety of formula (III) wherein R6, R7, R8and R9, are hydrogen or hydrocarbon groups; L is a divalent bridging group; M is an atom of a transition metal selected from those belonging to group 3, 4, 5, 6 or to the lanthanide or actinide groups in the Periodic Table of the Elements (new IUPAC version), X, same or different, is hydrogen, a halogen, a R10, OR10, OSO2CF3, OCOR10, SR10, NR102or PR102group, wherein the substituents R10are hydrogen or alkyl groups; p is an integer of from 1 to 3, being equal to the oxidation state of the metal M minus 2. The above metallocenes are particularly useful in the polymerization of propylene.
