- Synthesis of 1-Pyrroline by Denitrogenative Ring Expansion of Cyclobutyl Azides under Thermal Conditions
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We herein report an efficient and systematic synthesis of 1-pyrrolines from cyclobutyl azides under thermal and neutral conditions. The reaction proceeded without any additional reagents, and nitrogen was generated as the sole by-product. Furthermore, the generated 1-pyrrolines could be continuously transformed into pyrroles, N-Boc-amines, and oxaziridines in an one-pot manner. (Figure presented.).
- Ban, Kazuho,Miki, Yuya,Sajiki, Hironao,Sawama, Yoshinari,Tomita, Naohito
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p. 3481 - 3484
(2021/06/17)
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- Regio- And Stereoselective Synthesis of Thiazole-Containing Triarylethylenes by Hydroarylation of Alkynes
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Thiazole-containing π-conjugated moieties are important structural units in the development of new electronic and photochromic materials. We have developed a Pd-catalyzed syn-hydroarylation reaction of diaryl alkynes with thiazoles that provides access to thiazole-containing triarylethylenes. Pd(II) complexes derived from Pd(0) species and carboxylic acids facilitated C-H functionalization of the unsubstituted thiazole with high C5 selectivity. The catalytic system was also compatible with other azoles, such as oxazoles and a pyrazole, allowing the stereoselective syntheses of various trisubstituted olefins.
- Lee, Woohyeong,Shin, Changhoon,Park, Soo Eun,Joo, Jung Min
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p. 12913 - 12924
(2019/09/12)
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- Rhodium-catalyzed 2-methylthiolation reaction of thiazoles/oxazoles using 2-(methylthio)thiazole
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RhH(PPh3)4 and 1,3-bis(dicyclohexyl)phosphinopropane (dcypp) catalyze the 2-methylthiolation of oxazoles and thiazoles using 2-(methylthio)thiazole as a thiolating reagent. The methylthio transfer reaction is under equilibrium, and various 2-methylthiolated thiazoles and oxazoles were obtained in moderate to good yields by removing thiazole under refluxing o-dichlorobenzene.
- Arisawa, Mieko,Nihei, Yuri,Yamaguchi, Masahiko
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p. 939 - 949
(2015/03/04)
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- NaBH4-TMEDA and a palladium catalyst as efficient regio- and chemoselective system for the hydrodehalogenation of halogenated heterocycles
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The pair NaBH4-TMEDA as hydride source and a palladium catalyst in THF prove to be an efficient system for the hydrodehalogenation of halogenated heterocycles with one or more heteroatoms. In general, Pd(OAc) 2-PPh3 rapidly hydrodehalogenates reactive halo-heterocycles such as bromo-pyridines, -quinolines, -thiophenes, -indoles, -imidazoles, etc., at room temperature in very good yields, whereas in most cases PdCl2(dppf) reduces less reactive halides such as chloro-pyridines, -quinolines, -pyrimidines and bromo-indoles, -benzofurans, etc. Moreover, PdCl2(tbpf) shows to be even more active removing the 2- and 5-chlorine from both thiophene and thiazole rings. The reaction conditions tolerate various functional groups, allowing highly chemoselective reactions in the presence of halide, ester, alkyne, alkene and nitrile substituents. Moreover, with a proper selection of the catalyst it is also possible to obtain a good control in the regioselective hydrodehalogenation of a variety of polyhalogenated substrates.
- Chelucci, Giorgio,Figus, Susanna
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p. 191 - 209
(2014/07/21)
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- Programmed synthesis of arylthiazoles through sequential C-H couplings
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A programmed synthesis of privileged arylthiazoles via sequential C-H couplings catalyzed by palladium or nickel catalysts has been accomplished. This versatile protocol can supply all possible arylthiazole substitution patterns (2-aryl, 4-aryl, 5-aryl, 2
- Tani, Satoshi,Uehara, Takahiro N.,Yamaguchi, Junichiro,Itami, Kenichiro
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p. 123 - 135
(2014/01/06)
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- Novel series of 3-amino-N-(4-aryl-1,1-dioxothian-4-yl)butanamides as potent and selective dipeptidyl peptidase IV inhibitors
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A series of novel 3-amino-N-(4-aryl-1,1-dioxothian-4-yl)butanamides were investigated as dipeptidyl peptidase IV (DPP-4) inhibitors. Introduction of a 4-phenylthiazol-2-yl group showed highly potent DPP-4 inhibitory activity. Among various derivatives, (3R)-3-amino-N-(4-(4-phenylthiazol-2-yl)-tetrahydro-2H- thiopyran-4-yl)-4-(2,4,5-trifluorophenyl)butanamide 1,1-dioxide (30) reduced blood glucose excursion in an oral glucose tolerance test by oral administration.
- Nitta, Aiko,Fujii, Hideaki,Sakami, Satoshi,Satoh, Mikiya,Nakaki, Junko,Satoh, Shiho,Kumagai, Hiroki,Kawai, Hideki
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p. 7036 - 7040
(2013/01/15)
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- Room-temperature hydrodehalogenation of halogenated heteropentalenes with one or two heteroatoms
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The pair NaBH4-TMEDA as a hydride source and catalytic PdCl 2(dppf) in THF prove to be an efficient system for the hydrodehalogenation of bromo(chloro)-heteropentalenes with one or two heteroatoms, while Pd(OAc)2/PPh3 is able to reduce reactive haloheteropentalenes, and PdCl2(tbpf) allows the removal of the 2-chlorine from a thiophene ring. The reaction conditions tolerate various functional groups, allowing highly chemoselective reactions in the presence of halide, ester, alkyne, alkene, and nitrile substituents and also showing good efficiency in the regioselective hydrodehalogenation of a variety of polyhalogenated substrates.
- Chelucci, Giorgio,Baldino, Salvatore,Ruiu, Andrea
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p. 9921 - 9925,5
(2012/12/12)
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- Photochemistry of 3- and 5-phenylisothiazoles. Competing phototransposition pathways
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5-Phenylisothiazole undergoes phototransposition via the electrocyclic ring closure-heteroatom migration pathway and by the N2-C3 interchange reaction pathway. The latter route is enhanced by the addition of triethylamine (TEA) to the reaction medium and by increasing the polarity of the solvent. In addition to phototransposition, 5-phenylisothiazole also undergoes photocleavage to 2-cyano-1-phenylethenethiol which was trapped by reaction with benzyl bromide to yield 2-cyano-1-phenylethen-1-ylbenzyl thioether. 3-Phenylisothiazole also phototransposes by both reaction pathways, but the product distribution is not affected by the addition of TEA or by changing the solvent polarity.
- Pavlik, James W.,Tongcharoensirikul, Pakamas
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p. 3626 - 3631
(2007/10/03)
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- Phototransposition Chemistry of 4-Substituted Isothiazoles. The P4 Permutation Pathway
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Upon irradiation in the presence of a small quantity of base, 4-substituted isothiazoles undergo photocleavage to yield substituted cyanosulfides, which can be trapped as their benzyl thioether derivatives, and substituted isocyanosulfides. Both products are suggested to arise via initial photocleavage of the sulfur-nitrogen bond, resulting in the formation of a substituted β-thioformylvinyl nitrene, which can rearrange to the observed cyanosulfide, or cyclize to an undetected thioformylazirine. Deprotonation of the azirine leads directly to the isocyanosulfide. The plight of the isocyanosulfide depends on the C-4 substituent. If the substituent is aromatic, the isocyanosulfide is reprotonated at the isocyanide carbon and spontaneously cyclizes to a 4-substituted thiazole, the observed transposition product. If the substituent is not aromatic, the isocyanosulfide is reprotonated at sulfur and the resulting species has a higher energy barrier to cyclization. In these cases, the isocyanosulfides can be observed spectroscopically and can be trapped as their N-formylaminobenzyl thioether derivatives.
- Pavlik, James W.,Tongcharoensirikul, Pakamas,French, Kathleen M.
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p. 5592 - 5603
(2007/10/03)
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- Deamination of 2-aminothiazoles and 3-amino-1,2,4-triazines with nitric oxide in the presence of a catalytic amount of oxygen
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2-Aminothiazoles, 2-aminobenzazoles, and 3-amino-1,2,4-triazines were deaminated using nitric oxide (NO) in the presence of a catalytic amount of oxygen to afford corresponding unsubstituted heterocycles in good yields.
- Itoh, Takashi,Matsuya, Yuji,Nagata, Kazuhiro,Ohsawa, Akio
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p. 1547 - 1549
(2007/10/03)
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- Phototransposition chemistry of phenylisothiazoles and phenylthiazoles. 1. Interconversions in benzene solution
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Phenylthiazoles 1-3 and phenylisothiazoles 4-6 undergo phototransposition in benzene solvent mainly by P5, P6, and P7 permutation pathways. Phenylisothiazoles 5 and 6 also transpose via a P4 permutation process to yield phenylthiazoles 2 and 3 in less than 1% yield. In benzene saturated with D2O, 2-phenylthiazole (1) and 5-phenylisothiazole (6) each phototranspose to yield 4-deuterio-3-phenylisothiazole (4-D-4) and 4-phenylthiazole (2) without deuterium incorporation. Irradiation of 4-phenylthiazole (2) under these conditions results in rapid photodeuteration to yield 2-deuterio-4-phenylthiazole (2-D-2), which subsequently phototransposes to 5-deuterio-3-phenylisothiazole (5-D-3). These experimental results can be rationalized by a mechanism involving initial electrocyclic ring closure and sigmatropic shift of sulfur around the four sides of the azetine ring. Rearomatization of each bicyclic intermediate thus allows sulfur to insert into each position in the carbon-nitrogen sequence. As a consequence, these compounds divide into a tetrad in which isomers 1, 2,4, and 6 interconvert mainly via P5, P6, and P7 pathways and a dyad of two compounds in which 3 phototransposes to 5 via P5 and P7 pathways. Within the tetrad, BC-6, the bicyclic intermediate derived from 5-phenylisothiazoles (6), is postulated to undergo deuteration with simultaneous sigmatropic shift of sulfur when the reaction is carried out in benzene-D2O. This mechanistic view provides one coherent interpretation for the observed phototransposition and photodeuteration reactions.
- Pavlik, James W.,Tongcharoensirikul, Pakamas,Bird, Nigel P.,Day, A. Colin,Barltrop, John A.
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p. 2292 - 2300
(2007/10/02)
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- Palladium-Catalyzed Reactions of Terminal Acetylenes and Olefins with Halo-1,3-azoles
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The palladium-catalyzed reactions of 4-bromo- and 5-bromothiazoles, as well as 4-bromo and 5-bromooxazoles with terminal acetylenes gave ethynyl derivatives in 43-89percent yields, whereas the reactions of 2-bromothiazoles and iodo-N-methylimidazoles affo
- Sakamoto, Takao,Nagata, Hideo,Kondo, Yoshinori,Shiraiwa, Masafumi,Yamanaka, Hiroshi
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p. 823 - 828
(2007/10/02)
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- A NEW VAPOR-PHASE SYNTHESIS OF THIAZOLES
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The vapor-phase reaction of imines with sulfur dioxide to produce thiazoles has been studied at 450 - 500 deg C.Of the imines investigated acetone methyl imine was the most studied which produced 4-methylthiazole in 70percent yield.
- Amato, Joseph S.,Karady, Sandor,Phillips, Brian T.,Weinstock, Leonard M.
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p. 1947 - 1949
(2007/10/02)
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