Academic literature on the topic 'Pyrroles. Organic compounds'

Huanfeng Jiang of the South China University of Technology showed (J. Org. Chem. 2010, 75, 966) that an alkynoate 1 could be condensed with a 1,3-dicarbonyl compound 2 to give, under oxidizing conditions, the furan 3. Phil Ho Lee of Kangwon National University found (Tetrahedron Lett. 2010, 51, 1899) that the enyne 4 cyclized smoothly to the furan 5. Yahong Li of Suzhou University and Vladimir Gevorgyan of the University of Illinois, Chicago, demonstrated (J. Am. Chem. Soc. 2010, 132, 7645) that the cyclization of 6 proceeded with silyl migration, to give 7. François Bilodeau and Pat Forgione of Boehringer Ingelheim (Canada) optimized (J. Org. Chem. 2010, 75, 1550) the Pd-mediated decarboxylative coupling of a furoic acid 8 with 9 to give 10. This protocol also worked well with pyrrole carboxylic acids. In another transformation of a preformed pyrrole, Masatomo Iwao of Nagasaki University observed (Organic Lett. 2010, 12, 2734) that in the presence of LDA/diisopropylamine, the initially formed 2-anion from the deprotonation of 11 gave the 2-product 12 with more reactive electrophiles but the 5-product 13 with less reactive electrophiles. Umasish Jana of Jadavpur University developed (J. Org. Chem. 2010, 75, 1674) a route to more highly substituted pyrroles such as 17 using the remarkable four-component coupling of 14, 15, and 16 with nitromethane, the carbon of which was incorporated in the product. Laura L. Anderson, also of the University of Illinois, Chicago, designed (Organic Lett. 2010, 12, 2290) a clever approach to pyrroles, based on the Ir-catalyzed rearrangement of O-allyl oximes such as 18. Xiaofeng Tong of the East China University of Science and Technology reported (Chem. Commun. 2010, 312) the condensation of 20 with 21 to give the dihydropyridine 22. Base-mediated elimination of sulfinate could convert 22 into the pyridine. Jin-Quan Yu of Scripps/La Jolla found (Angew. Chem. Int. Ed. 2010, 49, 1275) that Pd-mediated activation of the nictotinamide 23 proceeded with high regioselectivity, leading to 25. Zhiping Li of Remnin University of China demonstrated (J. Org. Chem. 2010, 75, 4636) that the chloroenamine 26 cyclized to the indole 27 on exposure to NaI.

Masahiro Yoshida of the University of Tokushima described (Tetrahedron Lett. 2008, 49, 5021) the Pt-mediated rearrangement of alkynyl oxiranes such as 1 to the furan 2. Roman Dembinski of Oakland University reported (J. Org. Chem. 2008, 73, 5881) a related zinc-mediated rearrangement of propargyl ketones to furans. The cyclization of aryloxy ketones such as 3 to the benzofuran 4 developed (Tetrahedron Lett. 2008, 49, 6579) by Ikyon Kim of the Korea Research Institute of Chemical Technology is likely proceeding by a Friedel-Crafts mechanism. Sandro Cacchi and Giancarlo Fabrizi of Università degli Studi “La Sapienza”, Roma, observed (Organic Lett. 2008, 10, 2629) that base converted the enamine 5 to the pyrrole 6. Alternatively, oxidation of 5 with CuBr led to a pyridine. Zhuang-ping Zhuan of Xiamen University prepared (Adv. Synth. Cat. 2008, 350, 2778) pyrroles such as 9 by condensing an alkynyl carbinol 7 with a 1,3-dicarbonyl compound. Richard C. Larock of Iowa State University found (J. Org. Chem. 2008, 73, 6666) that combination of an alkynyl ketone 10 with 11 followed by oxidation with I-Cl led to the pyrazole 12. The “click” condensation of azides with alkynes, leading to the 1,4-disubstituted 1,2,3- triazole, has proven to be a powerful tool for combinatorial synthesis. Valery V. Fokin of Scripps/La Jolla and Zhenyang Lin and Guochen Jia of the Hong Kong University of Science and Technology have developed (J. Am. Chem. Soc. 2008, 130, 8923) a complementary approach, using Ru catalysts to prepare 1,5-disubstituted 1,2,3- triazoles. Remarkably, internal alkynes participate, and, as in the conversion of 13 to 15, propargylic alcohols direct the regioselectivity of the cycloaddition. A variety of methods have been put forward for functionalizing pyridines. Sukbok Chang of KAIST described (J. Am. Chem. Soc. 2008, 130, 9254) the direct oxidative homologation of a pyridine N -oxide 16 to give the unsaturated ester 18. Jonathan Clayden of the University of Manchester observed (Organic Lett. 2008, 10, 3567) that metalation of 19 gave an anion that rearranged to 20 with complete retention of enantiomeric excess. Shigeo Katsumura of Kwansei Gakuin University developed (Tetrahedron Lett. 2008, 49, 4349) an intriguing three-component coupling, combining 21, 22, and methanesulonamide 23 to give the pyridine 24.

Rubén Vicente and Luis A. López at the University of Oviedo in Spain reported (Angew. Chem. Int. Ed. 2012, 51, 8063) the synthesis of cyclopropyl furan 2 from alkylidene 1 and styrene by way of a zinc carbene intermediate. The same substrate 1 was also converted (Angew. Chem. Int. Ed. 2012, 51, 12128) to furan 3 via catalysis with tetrahydrothiophene in the presence of benzoic acid by J. Stephen Clark at the University of Glasgow. Xue-Long Hou at the Shanghai Institute of Organic Chemistry discovered (Org. Lett. 2012, 14, 5756) that palladacycle 6 catalyzes the conversion of bicyclic alkene 4 and alkynone 5 to furan 7. A silver-mediated C–H/C–H functionalization strategy for the synthesis of furan 9 from alkyne 8 and ethyl acetoacetate was developed (J. Am. Chem. Soc. 2012, 134, 5766) by Aiwen Lei at Wuhan University. Ning Jiao at Peking University and East China Normal University found (Org. Lett. 2012, 14, 4926) that azide 10 and aldehyde 11 could be converted to either pyrrole 12 or 13 with complete regiocontrol by judicious choice of a metal catalyst. Meanwhile, Michael A. Kerr at the University of Western Ontario developed (Angew. Chem. Int. Ed. 2012, 51, 11088) a multicomponent synthesis of pyrrole 16 involving the merger of nitrone 14 and the donor–acceptor cyclopropane 15. The pyrrole 16 was subsequently converted to an intermediate in the synthesis of the cholesterol-lowering drug compound Lipitor. A robust synthesis of the ynone trifluoroboronate 17 was developed (Org. Lett. 2012, 14, 5354) by James D. Kirkham and Joseph P.A. Harrity at the University of Sheffield, which thus allowed for the ready production of trifluoroboronate-substituted pyrazole 18. An alternative pyrazole synthesis via oxidative closure of unsaturated hydrazine 19 to produce 20 was reported (Org. Lett. 2012, 14, 5030) by Yu Rao at Tsinghua University. A unique fluoropyrazole construction was developed (Angew. Chem. Int. Ed. 2012, 51, 12059) by Junji Ichikawa at the University of Tsukuba that involved nucleophilic substitution of two of the fluorides in 21 to form pyrazole 22.

Considering the nature of organic contaminants in water, methods of their oxidative decomposition seem to be most appropriate for their removal from contaminated water. There are a lot of methods of chemical oxidation, however, Advanced Oxidation Processes (AOPs) seem to be the most suitable technologies for organic contaminants removal. AOPs belong to a group of processes that efficiently oxidize organic compounds towards harmless inorganic products such as water or carbon dioxide. The processes have shown great potential in treatment of pollutants of low or high concentrations and have found applications for various types of contamination. The hydroxyl radical (•OH) is oxidizing agent used at AOPs to drive contaminant decomposition. It is a powerful, non-selective chemical oxidant, which reacts very rapidly with most organic compounds. Another strong oxidizing agent, singlet oxygen, can be generated by photosensitization of phthalocyanines. Phthalocyanines are molecules based on pyrrol structures connected mainly with methionine groups (–CH=) having a metallic central atom. Illumination upon specific wavelengths initiates formation of singlet oxygen that attack organic contaminants.