Substituted Benzenes: The Garg Synthesis of Tubingensin A

2017 ◽  
Author(s):  
Douglass F. Taber
Keyword(s):  
Organic Chemistry ◽  
University Of Pennsylvania ◽  
Ni Catalyst ◽  
Indiana University ◽  
Aryl Iodide ◽  
Shanghai Institute ◽  
Peking University ◽  
Normal University ◽  
La Jolla ◽  
The University

John F. Hartwig of the University of California, Berkeley devised (Science 2014, 343, 853) conditions for the regioselective silylation of an arene 1 to give 2. The silyl group can directly be converted, inter alia, to halo, amino, alkyl, or hydroxyl. Jin-Quan Yu of Scripps La Jolla effected (Angew. Chem. Int. Ed. 2014, 53, 2683) regioselective alkenylation of the arene 3 with 4 to give 5. Wei-Liang Duan of the Shanghai Institute of Organic Chemistry described (Org. Lett. 2014, 16, 500) a related alkenyl­ation protocol. Deping Wang of Henyang Normal University developed (Eur. J. Org. Chem. 2014, 315) inexpensive conditions for the conversion of an aryl bromide 6 to the corre­sponding phenol 7. Mamoru Tobisu and Naoto Chatani of Osaka University used (J. Am. Chem. Soc. 2014, 136, 5587) a Ni catalyst to convert the lactam 8 to the aryl boro­nate 9. Patrick J. Walsh of the University of Pennsylvania found (Adv. Synth. Catal. 2014, 356, 165) conditions for the clean monoarylation of the amide 11 with 10 to give 12. In an application of the Catellani approach, Zhi- Yuan Chen of Jiangxi Normal University coupled (Chem. Eur. J. 2014, 20, 4237) the aryl iodide 13 with 14 to give the amino ester 15. Frederic Fabis of the Université de Caen-Basse-Normandie used (Chem. Eur. J. 2014, 20, 7507) Pd to catalyze the ortho halogenation (and alkoxylation) of the N-sulfonylamide 16 to give 17. Wen Wan of Shanghai University and Jian Hao of Shanghai University and the Shanghai Institute of Organic Chemistry effected (Chem. Commun. 2014, 50, 5733) ortho azidination of the aniline 18 with 19, leading to 20. Jianbo Wang of Peking University found (Angew. Chem. Int. Ed. 2014, 53, 1364) that the N-aryloxy amide 21 could be combined with the α-diazo ester 22 to give the ortho-alkenyl phenol 23. Silas P. Cook of Indiana University uncovered (Org. Lett. 2014, 16, 2026) remarkably simple conditions for the enantiospecific cyclization of 24 (65% ee) to 25 (63% ee). The development of arynes as reactive intermediates continues unabated. Xiaoming Zeng of Xi’an Jiaotong University developed (Org. Lett. 2014, 16, 314) the reagent 27 for the bis-functionalization of the aryne derived from 26.

Establishing Arrays of Stereogenic Centers: The Sato/Chida Synthesis of (-)-Kainic Acid

2013 ◽  
Author(s):  
Douglass F. Taber
Keyword(s):  
Catalyst System ◽  
Allylic Alcohol ◽  
University Of Pennsylvania ◽  
Ni Catalyst ◽  
Max Planck ◽  
Stereogenic Centers ◽  
University College London ◽  
Enantioselective Addition ◽  
La Jolla ◽  
The University

Benjamin List of the Max-Planck-Institut, Mülheim, devised (J. Am. Chem. Soc. 2010, 132, 10227) a catalyst system for the stereocontrolled epoxidation of a trisubstituted alkenyl aldehyde 1. Takashi Ooi of Nagoya University effected (Angew. Chem. Int. Ed. 2010, 49, 7562; see also Org. Lett. 2010, 12, 4070) enantioselective Henry addition to an alkynyl aldehyde 3. Madeleine M. Joullié of the University of Pennsylvania showed (Org. Lett. 2010, 12, 4244) that an amine 7 added selectively to an alkynyl aziridine 6. Yutaka Ukaji and Katsuhiko Inomata of Kanazawa University developed (Chem. Lett. 2010, 39, 1036) the enantioselective dipolar cycloaddition of 9 with 10. K. C. Nicolaou of Scripps/La Jolla observed (Angew. Chem. Int. Ed. 2010, 49, 5875; see also J. Org. Chem. 2010, 75, 8658) that the allylic alcohol from enantioselective reduction of 12 could be hydrogenated with high diastereocontrol. Masamichi Ogasawara and Tamotsu Takahashi of Hokkaido University added (Org. Lett. 2010, 12, 5736) the allene 14 to the acetal 15 with substantial stereocontrol. Helen C. Hailes of University College London investigated (Chem. Comm. 2010, 46, 7608) the enzyme-mediated addition of 18 to racemic 17. Dawei Ma of the Shanghai Institute of Organic Chemistry, in the course of a synthesis of oseltamivir (Tamiflu), accomplished (Angew. Chem. Int. Ed. 2010, 49, 4656) the enantioselective addition of 21 to 20. Shigeki Matsunaga of the University of Tokyo and Masakatsu Shibasaki of the Institute of Microbial Chemistry developed (Org. Lett. 2010, 12, 3246) a Ni catalyst for the enantioselective addition of 23 to 24. Juthanat Kaeobamrung and Jeffrey W. Bode of ETH-Zurich and Marisa C. Kozlowski of the University of Pennsylvania devised (Proc. Natl. Acad. Sci. 2010, 107, 20661) an organocatalyst for the enantioselective addition of 27 to 26. Yihua Zhang of China Pharmaceutical University and Professor Ma effected (Tetrahedron Lett. 2010, 51, 3827) the related addition of 27 to 29. There have been scattered reports on the stereochemical course of the coupling of cyclic secondary organometallics. In a detailed study, Paul Knochel of Ludwig-Maximilians- Universität München showed (Nat. Chem. 2020, 2, 125) that equatorial bond formation dominated, exemplified by the conversion of 31 to 33.

Stereoselective C-N Ring Construction

2011 ◽  
Author(s):  
Douglass Taber
Keyword(s):  
Organic Chemistry ◽  
Diels Alder ◽  
Wolff Rearrangement ◽  
Enantiomerically Pure ◽  
Amino Esters ◽  
Shanghai Institute ◽  
Single Diastereomer ◽  
Peking University ◽  
Convenient Route ◽  
The University

Ryoichi Kuwano of Kyushu University showed (J. Am. Chem. Soc. 2008, 130, 808) that diastereomerically and enantiomerically pure pyrollidines such as 2 could be prepared by hydrogenation of the corresponding pyrrole. Victor S. Martín of Universidad de la Laguna found (Organic Lett. 2008, 10, 2349) that the stereochemical outcome of the pyrrolidine-forming Nicholas cyclization could be directed by the protecting group on the N. Jianbo Wang of Peking University established (J. Org. Chem. 2008, 73, 1971) a convenient route to diazo esters such as 6. N-H insertion led to the pyrrolidine, which Zhen-Jiang Xu of the Shanghai Institute of Organic Chemistry and Chi-Ming Che of the University of Hong Kong showed (Organic Lett. 2008, 10, 1529) could be reduced with high diastereoselectivity to the hydroxy ester 7. Alternatively, Professor Wang found that photochemical Wolff rearrangement of 6 delivered the pyrrolidone 8 . Martin J. Slater and Shiping Xie of GlaxoSmithKline optimized (J. Org. Chem. 2008, 73, 3094) the hydroquinine catalyzed enantioselective 3+2 cycloaddition of 9 and 10, leading to the pyrrolidine 11 with high diastereocontrol. Shu Kobayashi of the University of Tokyo developed (Adv. Synth. Cat. 2008, 350, 647) a practical protocol for the aza Diels-Alder construction of enantiomerically-pure piperidines such as 14 . Biao Yu of the Shanghai Institute of Organic Chemistry cyclized (Tetrahedron Lett. 2008, 49, 672) the product from the proline-catalyzed enantioselective aldol of 15 and 16, leading to the substituted piperidine 17 . Michael Shipman of the University of Warwick described (Tetrahedron Lett. 2008, 49, 250) the cyclization of the aziridine derived from 18, that proceeded to give 19 as a single diastereomer, apparently via kinetic side-chain protonation. Takeo Kawabata of Kyoto University found (J. Am. Chem. Soc. 2008, 130, 4153) that intramolecular alkylation to form four, five and six-membered rings from amino esters such as 21 proceeded with remarkable enantioretention. Géraldine Masson and Jieping Zhu of CNRS, Gif-sur-Yvette, condensed (Organic Lett. 2008, 10, 1509) cinnamaldehyde 23 with cyanide and an ω-alkenyl amine to give the intramolecular aza-Diels-Alder substrate 24. Hongbin Zhai of the Shanghai Institute of Organic Chemistry acylated (J. Org. Chem. 2008, 73, 3589) 26 with 27, leading to the ring-closing metathesis precursor 28.

Transition-Metal Catalyzed Ring Construction: The Yu Synthesis of α-Agorafuran

2013 ◽  
Author(s):  
Douglass F. Taber
Keyword(s):  
Organic Chemistry ◽  
High Pressure ◽  
Ambient Conditions ◽  
High Pressure And Temperature ◽  
University Of Toronto ◽  
Peking University ◽  
Cu Catalyst ◽  
Metal Catalyzed ◽  
La Jolla ◽  
The University

Valery V. Fokin of Scripps/La Jolla extended (J. Am. Chem. Soc. 2010, 132, 2510) enantioselective Rh-mediated intermolecular cyclopropanation to α-olefins such as 1. Takahiro Nishimura and Tamio Hayashi of Kyoto University developed (Angew. Chem. Int. Ed. 2010, 49, 1638) a procedure for enantioselective intramolecular cyclopropanation, beginning with a propargyl sulfonamide 4. Gerhard Hilt of Philipps-Universität Marburg established (Organic Lett. 2010, 12, 1536) that an aryl alkyne 6 could add to cyclopentene to give the cyclobutene 7. Hajime Ito of Hokkaido University devised (J. Am. Chem. Soc. 2010, 132, 5990) a protocol for the borylation of an alkenyl silane 8 to give an intermediate α-lithio silane, which cyclized to the cyclobutane 9 with high diastereoconrol. Aryl alkenes worked as well. This same approach could be used to construct cyclopentanes and cyclohexanes. Zhi-Xiang Yu of Peking University showed (J. Am. Chem. Soc. 2010, 132, 4542) that the triene 10 cyclized to the cyclopentane 11 with high diastereocontrol. Yong Tang of the Shanghai Institute of Organic Chemistry optimized (Angew. Chem. Int. Ed. 2010, 49, 4463) a Cu catalyst for the enantioselective Nazarov cyclization of 12 to 13. The meso bis-carbonates 14 and 16 were prepared by singlet oxygenation of the inexpensive cyclopentadiene. Mark Lautens of the University of Toronto developed (J. Org. Chem. 2010, 75, 4056) a protocol for the enantioselective coupling of 14 to an arene boronic acid, giving the carbonate 15 with high enantiocontrol. Professor Ito devised (Angew. Chem. Int. Ed. 2010, 49, 560) a complementary procedure, coupling 16 with bis-pinacolatoborane to give an intermediate allylborinate, that then added to the aldehyde 18 to give 19 with high stereocontrol. It would be interesting to know if these procedures worked as well with the meso bis-carbonates derived from cyclohexadiene. Saim Özkar of Middle East Technical University prepared (J. Am. Chem. Soc. 2010, 132, 6541) Ru nanoclusters stabilized by a zeolite framework that effected hydrogenation of 20 at near ambient conditions, in contrast to the high pressure and temperature usually required.

Heteroaromatic Construction: The Wipf Synthesis of Cycloclavine

2013 ◽  
Author(s):  
Douglass F. Taber
Keyword(s):  
Organic Chemistry ◽  
Vinyl Ketone ◽  
Methyl Vinyl ◽  
Cross Metathesis ◽  
University Of Oxford ◽  
Fe Catalyst ◽  
Normal University ◽  
La Jolla ◽  
The University ◽  
Technological University

Wesley J. Moran of the University of Huddersfield cyclized (Tetrahedron Lett. 2011, 52, 2605) a propargylated ketone 1 with Au to give the furan 2. Shengming Ma of the Shanghai Institute of Organic Chemistry found (Synlett 2011, 931) that tri(2-furyl)phosphine catalyzed the rearrangement of cyclopropene diesters, prepared by the addition of diazomalonate to alkynes, to the corresponding alkoxy furan 4. Xihe Bi and Qian Zhang of Northeast Normal University established (Chem. Commun. 2011, 47, 809) that a simple Fe catalyst effected the condensation of 5 with 6 to give the pyrrole 7. Gianfranco Favi of the Università degli Studi di Urbino showed (J. Org. Chem. 2011, 76, 2860) that the three-component coupling of 8 with an amine 9 and a ketone 10 proceeded without catalyst to deliver the pyrrole 11. Timothy J. Donohoe of the University of Oxford homologated (Org. Lett. 2011, 13, 1036) 12 by cross-metathesis with methyl vinyl ketone, to give, after oxidation and condensation with NH4OAc, the substituted pyridine 13. Dale L. Boger of Scripps/La Jolla condensed ( Org. Lett. 2011, 13, 2492) the unsubstitued 1,2,3-triazine 15 with an enamine 14 to give 16. Shunsuke Chiba of Nanyang Technological University prepared (J. Am. Chem. Soc. 2011, 133, 6411) the pyridine 19 by oxidizing the cyclopropanol 17 in the presence of the alkenyl azide 18. Limin Wang of the East China University of Science and Technology prepared (Tetrahedron Lett. 2011, 52, 509) the 2-aminopyridine 23 by the four-component coupling of the aldehyde 20 and the ketone 22 with NH4OAc and malononitrile 21. Taking advantage of the Knochel protocol for aryl Grignard formation, Christopher J. Moody of the University of Nottingham combined (Chem. Commun. 2011, 47, 788) the adduct from 24 with the ketone 25 to give the indole 26. Carsten Bolm of RWTH Aachen extended (Org. Lett. 2011, 13, 2012) the Fe catalysis reported by Zheng to the azide 27 to give 28. Sang-gi Lee of Ewha Womans University found (Org. Lett. 2011, 13, 1350) that the Blaise adduct from the addition of 29 to the nitrile could be cyclized to the indole 30.

Heteroaromatic Construction: The Fukuyama Synthesis of Tryprostatin A

2013 ◽  
Author(s):  
Douglass F. Taber
Keyword(s):  
Organic Chemistry ◽  
University Of California ◽  
University Of Arkansas ◽  
Yale University ◽  
Au Catalyst ◽  
University Of Houston ◽  
Selective Substitution ◽  
Mcgill University ◽  
La Jolla ◽  
The University

Alessandro Palmieri of the University of Camerino developed (Synlett 2010, 2468) the condensation of a nitro acrylate 1 with a 1,3-dicarbonyl partner 2 to give the furan 3. Chaozhong Li of the Shanghai Institute of Organic Chemistry showed (Tetrahedron Lett. 2010, 51, 3678) that an alkenyl halide 4 could be cyclized to the furan 5. Ayhan S. Demir of Middle East Technical University established (Chem. Commun. 2010, 46, 8032) that a Au catalyst could catalyze the addition of an amine 7 to a cyanoester 6 to give the pyrrole 8 . Bruce A. Arndtsen of McGill University effected (Org. Lett. 2010, 12, 4916) the net three-component coupling of an imine 9, an acid chloride 10, and an alkyne 11 to deliver the pyrrole 12. Bernard Delpech of CNRS Gif-sur-Yvette prepared (Org. Lett. 2010, 12, 4760) the pyridine 15 by combining the diene 13 with the incipient carbocation 14. Max Malacria, Vincent Gandon, and Corinne Aubert of UPMC Paris optimized (Synlett 2010, 2314) the internal Co-mediated cyclization of a nitrile alkyne 5 to the tetrasubstituted pyridine 17. Yoshiaki Nakao of Kyoto University and Tamejiro Hiyama, now at Chuo University, effected (J. Am. Chem. Soc. 2010, 132, 13666) selective substitution of a preformed pyridine 18 at the C-4 position by coupling with an alkene 19. We showed (J. Org. Chem. 2010, 75, 5737) that the anion from deprotonation of a pyridine 21 could be added in a conjugate sense to 22 to give 23. Other particularly useful strategies for further substitution of preformed pyridines have been described by Olafs Daugulis of the University of Houston (Org. Lett. 2010, 12, 4277), by Phil S. Baran of Scripps/La Jolla (J. Am. Chem. Soc. 2010, 132, 13194), and by Robert G. Bergmann of the University of California, Berkeley, and Jonathan A. Ellman of Yale University (J. Org. Chem. 2010, 75, 7863). K. C. Majumdar of the University of Kalyani developed (Tetrahedron Lett. 2010, 51, 3807) the oxidative Pd-catalyzed cylization of 24 to the indole 25. Nan Zheng of the University of Arkansas showed (Org. Lett. 2010, 12, 3736) that Fe could be used to catalyze the rearrangement of the azirine 26 to the indole 27.

Substituted Benzenes: The Saikawa/Nakata Synthesis of Kendomycin

2013 ◽  
Author(s):  
Douglass F. Taber
Keyword(s):  
Alkyl Iodide ◽  
Benzene Derivative ◽  
State University ◽  
One Pot ◽  
Aryl Iodide ◽  
Peking University ◽  
Cu Catalyst ◽  
San Diego State University ◽  
University Of Massachusetts ◽  
The University

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.

Advances in Heterocyclic Aromatic Construction

2015 ◽  
Author(s):  
Tristan H. Lambert
Keyword(s):  
Metal Catalyst ◽  
Multicomponent Synthesis ◽  
Tsinghua University ◽  
Peking University ◽  
Donor Acceptor ◽  
Judicious Choice ◽  
Normal University ◽  
Drug Compound ◽  
Lowering Drug ◽  
The University

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.

Carbon–Carbon Bond Formation: The Bergman Synthesis of (+)-Fuligocandin B

2015 ◽  
Author(s):  
Douglass F. Taber
Keyword(s):  
Grignard Reagent ◽  
Alkyl Halide ◽  
Secondary Alcohol ◽  
Ni Catalyst ◽  
West Virginia University ◽  
Carbon Carbon Bond ◽  
Peking University ◽  
National University ◽  
The University ◽  
École Polytechnique

Xile Hu of the Ecole Polytechnique Fédérale de Lausanne optimized (J. Am. Chem. Soc. 2011, 133, 7084) a Ni catalyst for the coupling of a Grignard reagent 2 with a secondary alkyl halide 1. Duk Keun An of Kangwon National University devised (Tetrahedron Lett. 2011, 52, 1718; Chem. Commun. 2011, 47, 3281) a strategy for the reductive coupling of an ester 4 with a Grignard reagent 2 to give the secondary alcohol. Daniel J. Weix of the University of Rochester added (Org. Lett. 2011, 13, 2766) the halide 7 in a conjugate sense to the bromoenone 6, setting the stage for further organometallic coupling. James Y. Becker of the Ben-Gurion University of the Negev effected (J. Org. Chem. 2011, 76, 4710) Kolbe coupling of the silyl acid 9 to give the decarboxylated dimer 10. Shi-Kai Tian of USTC Hefei showed (Chem. Commun. 2011, 47, 2158) that depending on the sulfonyl group used, the coupling of 11 with 12 could be directed cleanly toward either the Z or the E product. Yoichiro Kuninobu and Kazuhiko Takai of Okayama University added (Org. Lett. 2011, 13, 2959) the sulfonyl ketone 14 to the alkyne 13 to form the trisubstituted alkene 15. Jianbo Wang of Peking University assembled (Angew. Chem. Int. Ed. 2011, 50, 3510) the trisubstituted alkene 18 by adding the diazo ester 16 to the alkyne 17. Gangguo Zhu of Zhejiang Normal University constructed (J. Org. Chem. 2011, 76, 4071) the versatile tetrasubstituted alkene 21 by adding the chloroalkyne 19 to acrolein 20. Other more substituted acceptors worked as well. Chunxiang Kuang of Tongji University and Qing Yang of Fudan University effected (Tetrahedron Lett. 2011, 52, 992) elimination of 22 to 23 by stirring with Cs2CO3 at 115°C in DMSO overnight. Toshiaki Murai of Gifu University created (Chem. Lett. 2011, 40, 70) a propargyl anion by condensing 24 with 25 then adding 26. Xiaodong Shi of West Virginia University found (Org. Lett. 2011, 13, 2618) that the enantiomerically enriched propargyl ether 29 could be rearranged to the trisubsituted allene 30 with retention of the ee and with high de.

Heteroaromatics: The Zhou/Li Synthesis of Goniomitine

2017 ◽  
Author(s):  
Douglass F. Taber
Keyword(s):  
Organic Chemistry ◽  
Oxidative Cyclization ◽  
Silyl Ether ◽  
Keto Ester ◽  
Transfer Protein ◽  
Shanghai Institute ◽  
Lanzhou Institute ◽  
Institute Of Technology ◽  
The University ◽  
Technological University

Xin-Yan Wu of East China University of Science and Technology and Jun Yang of the Shanghai Institute of Organic Chemistry added (Tetrahedron Lett. 2014, 55, 4071) the Grignard reagent 1 to propargyl alcohol 2 to give an intermediate that could be bory­lated, then coupled under Pd catalysis with an anhydride, leading to the furan 3. Fuwei Li of the Lanzhou Institute of Chemical Physics constructed (Org. Lett. 2014, 16, 5992) the furan 6 by oxidizing the keto ester 4 in the presence of the enamide 5. Yuanhong Liu of the Shanghai Institute of Organic Chemistry prepared (Angew. Chem. Int. Ed. 2014, 53, 11596) the pyrrole 9 by reducing the azadiene 7 with the Negishi reagent, then adding the nitrile 8. Yefeng Tang of Tsinghua University found (Tetrahedron Lett. 2014, 55, 6455) that the Rh carbene derived from 11 could be added to an enol silyl ether 10 to give the pyrrole 12. Pazhamalai Anbarasan of the Indian Institute of Technology Madras reported (J. Org. Chem. 2014, 79, 8428) related results. Zheng Huang of the Shanghai Institute of Organic Chemistry established (Angew. Chem. Int. Ed. 2014, 53, 1390) a connection between substituted piperidines and pyridines by dehydrogenating 13 to 15, with 14 as the acceptor. Joseph P. A. Harrity of the University of Sheffield conceived (Chem. Eur. J. 2014, 20, 12889) the cascade assembly of the pyridine 18 by cycloaddition of 16 with 17 followed by Pd-catalyzed coupling. Teck-Peng Loh of Nanyang Technological University converted (Org. Lett. 2014, 16, 3432) the keto ester 19 into the azirine, then eliminated it to form an aza­triene that cyclized to the pyridine 20. En route to a cholesteryl ester transfer protein inhibitor, Zhengxu S. Han of Boehringer Ingelheim combined (Org. Lett. 2014, 16, 4142) 21 with 22 to give an intermediate that could be oxidized to 23. Magnus Rueping of RWTH Aachen used (Angew. Chem. Int. Ed. 2014, 53, 13264) an Ir photoredox catalyst in conjunction with a Pd catalyst to cyclize the enamine 24 to the indole 25. Yingming Yao and Yingsheng Zhao of Soochow University effected (Angew. Chem. Int. Ed. 2014, 53, 9884) oxidative cyclization of 26 to 27.

Metal-Mediated C–C Ring Construction: The Lei Synthesis of (−)-Huperzine Q

2017 ◽  
Author(s):  
Douglass F. Taber
Keyword(s):  
Organic Chemistry ◽  
Conjugate Addition ◽  
Harvard University ◽  
Unsaturated Ester ◽  
Pd Catalyst ◽  
Enantiomerically Pure ◽  
Shanghai Institute ◽  
Diastereoselective Addition ◽  
University Of Bristol ◽  
The University

Following the Szymoniak protocol, Morwenna S. M. Pearson-Long and Philippe Bertus of the Université du Maine added (Synthesis 2015, 47, 992) the Grignard rea­gent 2 to the nitrile 1 to give the cyclopropyl amine 3. Chen-Guo Feng of the Shanghai Institute of Organic Chemistry prepared (Chem. Commun. 2015, 51, 8773) the cyclobutane 6 by enantioselective conjugate addition of 5 to the unsaturated ester 4. Martin Kotora of Charles University showed (Eur. J. Org. Chem. 2015, 2868) that the zirconacycle from the eneyne 7 reacted with the aldehyde 8 to give, after iodina­tion, the alcohol 9. Xiaoming Feng of Sichuan University used (Angew. Chem. Int. Ed. 2015, 54, 1608) a scandium catalyst to effect the intramolecular Roskamp cyclization of 10 to 11. Celia Dominguez of CHDI observed (Org. Lett. 2015, 17, 1401) that the double alkylation of the ester 12 with the dibromide 13 proceeded with high diaste­reoselectivity, to give 14. Hirokazu Tsukamoto of Tohoku University cyclized (Chem. Commun. 2015, 51, 8027) 15 to 16 in high ee. Daniel J. Weix of the University of Rochester found (J. Am. Chem. Soc. 2015, 137, 3237) that under the influence of an enantiomerically-pure Ti catalyst, the organon­ickel species derived from 18 opened the prochiral epoxide 17 to give 19 in high ee. John F. Bower of the University of Bristol optimized (J. Am. Chem. Soc. 2015, 137, 463) conditions for the highly diastereoselective Rh-mediated cyclocarbonylation of 20 to 21. Margaret A. Brimble of the University of Auckland initiated (J. Org. Chem. 2015, 80, 2231) the construction of the cyclohexenone 24 by the diastereoselective addition of 23 to the unsaturated ester 22. Olivier Baslé and Marc Maduit of ENSC Rennes devised (Chem. Eur. J. 2015, 21, 993) conditions for the preparation of 26 by enantioselective conjugate addition to the cyclohexenone 25. Yoshito Kishi of Harvard University demonstrated (Tetrahedron Lett. 2015, 56, 3220) that the carbenoid generated from the epoxide 27 cyclized to 28 with high dia­stereoselectivity. Wenjun Tang, also of the Shanghai Institute of Organic Chemistry, developed (Angew. Chem. Int. Ed. 2015, 54, 3033) a Pd catalyst for the diastereoselec­tive (because it is enantioselective) cyclization of 29 to 30.

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