Substituted Benzenes: The Saikawa/Nakata Synthesis of Kendomycin

Author(s):  
Douglass F. Taber

Jianbo Wang of Peking University described (Angew. Chem. Int. Ed. 2010, 49, 2028) the Au-promoted bromination of a benzene derivative such as 1 with N-bromosuccinimide. In a one-pot procedure, addition of a Cu catalyst followed by microwave heating delivered the aminated product 2. Jian-Ping Zou of Suzhou University and Wei Zhang of the University of Massachusetts, Boston, observed (Tetrahedron Lett. 2010, 51, 2639) that the phosphonylation of an arene 3 proceeded with substantial ortho selectivity. Yonghong Gu of the University of Science and Technology, Hefei, showed (Tetrahedron Lett. 2010, 51, 192) that an arylpropanoic acid 6 could be ortho hydroxylated with PIFA to give 7. Louis Fensterbank, Max Malacria, and Emmanuel Lacôte of UMPC Paris found (Angew. Chem. Int. Ed. 2010, 49, 2178) that a benzoic acid could be ortho aminated by way of the cyano amide 8. Daniel J. Weix of the University of Rochester developed (J. Am. Chem. Soc. 2010, 132, 920) a protocol for coupling an aryl iodide 10 with an alkyl iodide 11 to give 12. Professor Wang devised (Angew. Chem. Int. Ed. 2010, 49, 1139) a mechanistically intriguing alkyl carbonylation of an iodobenzene 10. This is presumably proceeding by way of the intermediate diazo alkane. Usually, benzonitriles are prepared by cyanation of the halo aromatic. Hideo Togo of Chiba University established (Synlett 2010, 1067) a protocol for the direct electrophilic cyanation of an electron-rich aromatic 15. Thomas E. Cole of San Diego State University observed (Tetrahedron Lett. 2010, 51, 3033) that an alkyl dimethyl borane, readily prepared by hydroboration of the alkene with BCl3 and Et3 SiH, reacted with benzoquinone 17 to give 18. Presumably this transformation could also be applied to substituted benzoquinones. When a highly substituted benzene derivative is needed, it is sometimes more economical to construct the aromatic ring. Joseph P. A. Harrity of the University of Sheffield and Gerhard Hilt of Philipps-Universität Marburg showed (J. Org. Chem. 2010, 75, 3893) that the Co-catalyzed Diels-Alder cyloaddition of alkynyl borinate 21 with a diene 20 proceeded with high regiocontrol, to give, after oxidation, the aryl borinate 22.

Author(s):  
Douglass Taber

Several elegant methods for the enantioselective transformation of preformed prochiral rings have been put forward. Derek R. Boyd of Queen’s University, Belfast devised (Chem. Commun. 2008, 5535) a Cu catalyst that effected allylic oxidation of cyclic alkenes such as 1 with high ee. Christoph Jaekel of the Ruprecht-Karls-Universität Heidelberg established (Adv. Synth. Cat. 2008, 350, 2708) conditions for the enantioselective hydrogenation of cyclic enones such as 3. Marc L. Snapper of Boston College developed (Angew. Chem. Int. Ed. 2008, 47, 5049) a Cu catalyst for the enantioselective allylation of activated cyclic enones such as 5. Alexandre Alexakis of the University of Geneva showed (Angew. Chem. Int. Ed. 2008, 47, 9122) that dienones such as 8 could be induced to undergo 1,4 addition, again with high ee. Tsutomu Katsuki of Kyushu University originated (J. Am. Chem. Soc. 2008, 130, 10327) an Ir catalyst for the addition of diazoacetate 11 to alkenes such as 10 to give the cyclopropane 12 with high chemo-, enantio- and diastereoselectivity. Weiping Tang of the University of Wisconsin found (Angew. Chem. Int. Ed. 2008, 47, 8933) a silver catalyst that rearranged cyclopropyl diazo esters such as 13 to the cyclobutene 14 with high regioselectivity. Zhang-Jie Shi of Peking University demonstrated (J. Am. Chem. Soc. 2008, 130, 12901) that under oxidizing conditions, a Pd catalyst could cyclize 15 to 16. Sergio Castillón of the Universitat Rovira i Virgili, Tarragona devised (Organic Lett. 2008, 10, 4735) a Rh catalyst for the enantioselective cyclization of 17 to 18. Virginie Ratovelomanana-Vidal of the ENSCP Paris and Nakcheol Jeong of Korea University established (Adv. Synth. Cat. 2008, 350, 2695) conditions for the enantioselective intramolecular Pauson-Khand cyclization of 19 to give, after hydrolysis, the cyclopentenone 20. Quanrui Wang of Fudan University, Several elegant methods for the enantioselective transformation of preformed prochiral rings have been put forward. Derek R. Boyd of Queen’s University, Belfast devised (Chem. Commun. 2008, 5535) a Cu catalyst that effected allylic oxidation of cyclic alkenes such as 1 with high ee.


Author(s):  
Douglass Taber

Chaozhong Li of the Shanghai Institute of Organic Chemistry demonstrated (Organic Lett. 2008, 10, 4037) facile and selective Cu-catalyzed β-lactam formation, converting 1 to 2. Paul Helquist of the University of Notre Dame devised (Organic Lett. 2008, 10, 3903) an effective catalyst for intramolecular alkyne hydroamination, converting 3 into the imine 4. Six-membered ring construction worked well also. Jon T. Njardarson of Cornell University found (Organic Lett. 2008, 10, 5023) a Cu catalyst for the rearrangement of alkenyl aziridines such as 5 to the pyrroline 6. Philippe Karoyan of the UPMC, Paris developed (J. Org. Chem. 2008, 73, 6706) an interesting chiral auxiliary directed cascade process, converting the simple precursor 7 into the complex pyrrolidine 9. Sherry R. Chemler of the State University of New York, Buffalo devised (J. Am. Chem. Soc. 2008, 130, 17638) a chiral Cu catalyst for the cyclization of 10, to give 12 with substantial enantiocontrol. Wei Wang of the University of New Mexico demonstrated (Chem. Commun. 2008, 5636) the organocatalyzed condensation of 13 and 14 to give 16 with high enantio- and diastereocontrol. Two complementary routes to azepines/azepinones have appeared. F. Dean Toste of the University of California, Berkeley showed (J. Am. Chem. Soc. 2008, 130, 9244) that a gold complex catalyzed the condensation of 17 and 18 to give 19. Frederick G. West of the University of Alberta found (Organic Lett. 2008, 10, 3985) that lactams such as 20 could be ring-expanded by the addition of the propiolate anion 21. Takeo Kawabata of Kyoto University extended (Organic Lett . 2008, 10, 3883) “memory of chirality” studies to the cyclization of 23, demonstrating that 24 was formed in high ee. Paul V. Murphy of University College Dublin took advantage (Organic Lett . 2008, 10, 3777) of the well-known intramolecular addition of azides to alkenes, showing that the intermediate could be intercepted with nucleophiles such as thiophenol, to give the cyclized product 26 with high diastereocontrol.


Author(s):  
Tristan H. Lambert

A reductive radical cyclization of tetrahydropyran 1 to form bicycle 2 using iron(II) chloride in the presence of NaBH4 was reported (Angew. Chem. Int. Ed. 2012, 51, 6942) by Louis Fensterbank and Cyril Ollivier at the University of Paris and Anny Jutand at the Ecole Normale Supérieure. The enantioselective conversion of tetrahydrofuran 3 to spirocycle 5 via iminium ion-catalyzed hydride transfer/cyclization was developed (Angew. Chem. Int. Ed. 2012, 51, 8811) by Yong-Qiang Tu at Lanzhou University. Daniel Romo at Texas A&M University showed (J. Am. Chem. Soc. 2012, 134, 13348) that enantioenriched tricyclic β-lactone 8 could be readily prepared via dyotropic rearrangement of the diketoacid 6 under catalysis by chiral Lewis base 7. A dyotropic rearrangement was also utilized (Angew. Chem. Int. Ed. 2012, 51, 6984) by Zhen Yang at Peking University, Tuoping Luo at H3 Biomedicine in Cambridge, MA, and Yefeng Tang at Tsinghua University for the conversion of 9 to the bicyclic lactone 10. In terms of the enantioselective synthesis of β-lactones, Karl Scheidt at Northwestern University found that NHC catalyst 12 effects (Angew. Chem. Int. Ed. 2012, 51, 7309) the dynamic kinetic resolution of aldehyde 11 to furnish the lactone 13 with very high ee. Meanwhile, Xiaomeng Feng at Sichuan University has developed (J. Am Chem. Soc. 2012, 134, 17023) a rare example of an enantioselective Baeyer-Villiger oxidation of 4-alkyl cyclohexanones such as 14. The diastereoselective preparation of tetrahydropyran 18 by Lewis acid-promoted cyclization of cyclopropane 17 was accomplished (Org. Lett. 2012, 14, 6258) by Jin Kun Cha at Wayne State University. Stephen J. Connon at the University of Dublin reported (Chem. Commun. 2012, 48, 6502) the formal cycloaddition of aryl succinic anhydrides such as 18 with aldehydes to produce γ-butyrolactones, including 20, in high ee. The stereodivergent cyclization of 21 via desilylation-induced heteroconjugate addition to produce the complex tetrahydropyran 22 was discovered (Org. Lett. 2012, 14, 5550) by Paul A. Clarke at the University of York. Remarkably, while TFA produced a 13:1 diastereomeric ratio in favor of the cis diastereomer 22, the use of TBAF resulted in complete reversal of diastereoselectivity.


Author(s):  
Douglass F. Taber

Carlo Siciliano and Angelo Liguori of the Università della Calabria showed (J. Org. Chem. 2012, 77, 10575) that an amino acid 1 could be both protected and activated with Fmoc-Cl, so subsequent exposure to diazomethane delivered the Fmoc-protected diazo ketone 2. Pei-Qiang Huang of Xiamen University activated (Angew. Chem. Int. Ed. 2012, 51, 8314) a secondary amide 3 with triflic anhydride, then added an alkyl Grignard reagent with CeCl3 to give an intermediate that was reduced to the amine 4. John C. Walton of the University of St. Andrews found (J. Am. Chem. Soc. 2012, 134, 13580) that under irradiation, titania could effect the decarboxylation of an acid 5 to give the dimer 6. Jin Kun Cha of Wayne State University demonstrated (Angew. Chem. Int. Ed. 2012, 51, 9517) that a zinc homoenolate derived from 7 could be transmetalated, then coupled with an electrophile to give the alkylated product 8. The Ramberg-Bäcklund reaction is an underdeveloped method for the construction of alkenes. Adrian L. Schwan of the University of Guelph showed (J. Org. Chem. 2012, 77, 10978) that 10 is a particularly effective brominating agent for this transformation. Daniel J. Weix of the University of Rochester coupled (J. Org. Chem. 2012, 77, 9989) the bromide 12 with the allylic carbonate 13 to give 14. The Julia-Kocienski coupling, illustrated by the addition of the anion of 16 to the aldehyde 15, has become a workhorse of organic synthesis. In general, this reaction is E selective. Jirí Pospísil of the University Catholique de Louvain demonstrated (J. Org. Chem. 2012, 77, 6358) that inclusion of a K+-sequestering agent switched the selectivity to Z. Yoichiro Kuninobu, now at the University of Tokyo, and Kazuhiko Takai of Okayama University constructed (Org. Lett. 2012, 14, 6116) the tetrasubstituted alkene 20 with high geometric control by the Re-catalyzed addition of 19 to the alkyne 18. André B. Charette of the Université de Montréal converted (Org. Lett. 2012, 14, 5464) the allylic halide 21 to the alkyne 22 by displacement with iodoform followed by elimination. In an elegant extension of his studies with alkyl tosylhydrazones, Jianbo Wang of Peking University added (J. Am. Chem. Soc. 2012, 134, 5742) an alkyne 24 to 23 to give 25.


Author(s):  
Douglass F. Taber

Stephen G. DiMagno of the University of Nebraska developed (Chem. Eur. J. 2015, 21, 6394) a protocol for the clean monoiodination of 1 to 2. The bromomethylation (or chloromethylation, with HCl) of a benzene derivative is straightforward with formal­dehyde and HBr. Naofumi Tsukada of Shizuoka University designed (Organometallics 2015, 34, 1191) a Cu catalyst that mediated the coupling of an alkyne with the benzyl bromide so produced, effecting net propargylation of 3 with 4 to give 5. Triazenes such as 7, versatile intermediates for organic synthesis, are usually prepared by diazotization of the corresponding aniline. Kay Severin of the Ecole Polytechnique Fédérale de Lausanne established (Angew. Chem. Int. Ed. 2015, 54, 302) an alternative route from the aryl Grignard reagent 6. Ping Lu and Yanguang Wang of Zhejiang University showed (Chem. Commun. 2015, 51, 2840) that dimethylformamide could serve as the carbon source for the conversion of 8 to the nitrile 9. Junha Jeon of the University of Texas at Arlington effected (J. Org. Chem. 2015, 80, 4661; Chem. Commun. 2015, 51, 3778) the reductive ortho silylation of 10 to give 11. Vladimir Gevorgyan of the University of Illinois at Chicago found (Angew. Chem. Int. Ed. 2015, 54, 2255) that the phenol derivative 12 could be ortho carboxylated, leading to 13. Lutz Ackermann of the Georg-August-Universität Göttingen, starting (Chem. Eur. J. 2015, 21, 8812) with the designed amide 14, effected ortho metala­tion followed by coupling, to give the methylated product 15. Tetsuya Satoh and Masahiro Miura of Osaka University used (Org. Lett. 2015, 17, 704) the dithiane of 16 to direct ortho metalation. Coupling with acrylate followed by reductive desulfu­rization led to the ester 17. Jin-Quan Yu of Scripps/La Jolla designed (Angew. Chem. Int. Ed. 2015, 54, 888) the phenylacetamide 18 to direct selective meta metalation, leading to the unsat­urated aldehyde 19. In an extension of the Catellani protocol, Guangbin Dong of the University of Texas prepared (J. Am. Chem. Soc. 2015, 137, 5887) the biphenyl 21 by net meta metalation of the benzylamine 20. Several methods for the de novo assembly of benzene derivatives have recently been put forward. Rajeev S. Menon of the Indian Institute of Chemical Technology condensed (Org. Lett. 2015, 17, 1449) the unsaturated aldehyde 22 with the sulfonyl ester 23 to give 24.


Philosophy ◽  
2001 ◽  
Vol 76 (1) ◽  
pp. 3-4

Hasok ChangLecturer in Philosophy of Science at University College London. His chief research interests are in the history and philosophy of the physical sciences from the 18th century onwards.Fiona EllisLecturer in Philosophy at Wadham College, Oxford. She works in metaphilosophy, metaphysics, and aesthetics. An article on Sartre is forthcoming in Sartre Studies.James SomervilleLecturer in Philosophy at the University of Hull. He is author of The Enigmatic Parting Shot. His book The Epistemological Significance of the Interrogative is in preparation.J. Angelo CorlettProfessor of Philosophy at San Diego State University. He is author of Responsibility and Punishment (Kluwer, forthcoming) and Analyzing Social Knowledge (Rowman & Littlefield, 1996), as well as over 50 articles on moral, social, political and legal philosophy, and epistemology. He is also the founding Editor-in-Chief of The Journal of Ethics: An International Philosophical Review.Charles TaliaferroProfessor of Philosophy, St Olaf College. He is currently writing The Evolution of Modern Philosophy of Religion (Cambridge University Press).Stephen HetheringtonAssociate Professor of Philosophy at the University of New South Wales in Sydney, Australia. He is the author of two books, Epistemology's Paradox (Rowman & Littlefield, 1992) and Knowledge Puzzles (Westview Press, 1996).Timothy ChappellLecturer in Philosophy at the University of Dundee. He has published books on ancient philosophy (Aristotle and Augustine on Freedom of Action; The Plato Reader), edited a collection on environmental philosophy (The Philosophy of the Environment), and most recently argued for an Aristotelian pluralism in ethics in Understanding Human Goods.Jenny TeichmanAn Emerita Fellow of New Hall in the University of Cambridge. Her previous publications in Philosophy include papers on personhood, on terrorism and on Derrida, Her last two books are Social Ethics (Blackwell) and Polemical Papers (Ashgate).


Author(s):  
Kathleen A. Krentler ◽  
Albert Caruana

A transnational partnership between the University of Malta in Malta and San Diego State University in the United States resulted in an agreement to commence a Masters degree in Integrated Marketing Communications. The degree is fully delivered in Malta, a Mediterranean island state and a full member of the European Union. In Malta, the program is held not at the main campus of the University but at the historical campus of the University of Malta in Valetta that dates back to 1592. Classes are in English and are taught by faculty from both universities. Students earn a degree from each of the two participating schools thus providing recognition in both the US and the EU. This chapter charts the challenges faced and the hurdles encountered to develop the curriculum, launch the degree, recruit the students, undertake teaching, and ultimately, graduate the first cohort.


Author(s):  
Allison K. Griffith ◽  
Tristan H. Lambert

The α-C–H functionalization of piperidine catalyzed by tantalum complex 1 to pro­duce amine 2 was developed (Org. Lett. 2013, 15, 2182) by Laurel L. Schafer at the University of British Columbia. An asymmetric diamination of diene 3 with diaziri­dine reagent 4 under palladium catalysis to furnish cyclic sulfamide 5 was developed (Org. Lett. 2013, 15, 796) by Yian Shi at Colorado State University. Enantioenriched β-fluoropiperdine 8 was prepared (Angew. Chem. Int. Ed. 2013, 52, 2469) via amino­fluorocyclization of 6 with hypervalent iodide 7, as reported by Cristina Nevado at the University of Zurich. Erick M. Carreira at ETH Zürich disclosed (J. Am. Chem. Soc. 2013, 135, 6814) a ruthenium-catalyzed hydrocarbamoylation of allylic formamide 9 to yield pyrrolidone 10. Hans-Günther Schmalz at the University of Köln disclosed (Angew. Chem. Int. Ed. 2013, 52, 1576) an asymmetric hydrocyanation of styrene 11 with Ni(cod)₂ and phosphine–phosphite ligand 12 to yield exclusively the branched cyanide 13. A simi­lar transformation of styrene 11 to the hydroxycarbonylated product 15 was catalyzed (Chem. Commun. 2013, 49, 3306) by palladium complex 14, as reported by Matthew L. Clarke at the University of St Andrews. Feng-Ling Qing at the Chinese Academy of Sciences found (Angew. Chem. Int. Ed. 2013, 52, 2198) that the hydrotrifluoromethylation of unactivated alkene 16 to 17 was catalyzed by silver nitrate. The same transformation was also reported (J. Am.Chem. Soc. 2013, 135, 2505) by Véronique Gouverneur at the University of Oxford using a ruthenium photocatalyst and the Umemoto reagent 18. Clark R. Landis at the University of Wisconsin, Madison reported (Angew. Chem. Int. Ed. 2013, 52, 1564) a one-pot asymmetric hydroformylation using 21 followed by Wittig olefination to transform alkene 19 into the γ-chiral α,β-unsaturated carbonyl compound 20. Debabrata Mati at the Indian Institute of Technology Bombay found (J. Am. Chem. Soc. 2013, 135, 3355) that alkene 22 could be nitrated stereoselectively with silver nitrite and TEMPO to form alkene 23. Damian W. Young at the Broad Institute disclosed (Org. Lett. 2013, 15, 1218) that a macrocyclic vinylsiloxane 24, which was synthesized via an E-selective ring clos­ing metathesis reaction, could be functionalized to make either E- or Z-alkenes, 25 and 26.


Author(s):  
Douglass F. Taber

Thomas R. Hoye of the University of Minnesota devised (Nature 2013, 501, 531) the reagent 2, that cyclized to a benzyne that in turn dehydrogenated the alkane 1 to the alkene 3, and 4. Abigail G. Doyle of Princeton University developed (J. Am. Chem. Soc. 2013, 135, 12990) a reagent combination for the allylic fluorination of a terminal alkene 5 to the branched product 6. Yan Zhang and Jianbo Wang of Peking University oxidized (Angew. Chem. Int. Ed. 2013, 52, 10573) the methyl group of 7 to give the nitrile 8. Hanmin Huang of the Lanzhou Institute of Chemical Physics found (Org. Lett. 2013, 15, 3370) conditions for the carbonylation of the benzylic site of 9, leading to coupling with 10 to form the amide 11. Yu Rao of Tsinghua University effected (Angew. Chem. Int. Ed. 2013, 52, 13606) the direct methoxylation of 12, to give 13. Pd-mediated methoxylation had previously been described (Chem. Sci. 2013, 4, 4187) by Bing-Feng Shi of Zhejiang University. M. Christina White of the University of Illinois, Urbana found (J. Am. Chem. Soc. 2013, 135, 14052) that with variant ligands on the Fe catalyst, the oxidation of 14 could be directed selectively to either 15 or 16. C–H bonds can also be converted to C–N bonds. Sukbok Chang of KAIST oxi­dized (J. Am. Chem. Soc. 2013, 135, 12861) the unsaturated ester 17 with 18 to form the enamide 18. Gong Chen of Pennsylvania State University cyclized (Angew. Chem. Int. Ed. 2013, 52, 11124) the amide 20 to the γ-lactam 21. Professor Shi reported (Angew. Chem. Int. Ed. 2013, 52, 13588) a related approach to β-lactams. Ethers are easily oxidized. Taking advantage of this, Yun Liang of Hunan Normal University coupled (Synthesis 2013, 45, 3137) the bromoalkyne 23 with tetrahydro­furan 22 to give 24. Guangbin Dong of the University of Texas, Austin devised (J. Am. Chem. Soc. 2013, 135, 17747) a protocol for the β-arylation of ketones, includ­ing the preparation of 27 by the coupling of 25 with 26.


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