Construction of Stereochemical Arrays

Author(s):  
Tristan H. Lambert

The unprecedented enantioselective 1,8-addition of azlactone 1 to acylpyrrole 2 catalyzed by triaminophosphorane 3 was reported (J. Am. Chem. Soc. 2012, 134, 19370) by Takashi Ooi at Nagoya University. Tomislav Rovis at Colorado State University developed (Angew. Chem. Int. Ed. 2012, 51, 12330) the asymmetric oxidative hetero-Diels-Alder reaction of propionaldehyde (5) and ketone 6 to produce lactone 8, catalyzed by NHC catalyst 7 in the presence of phenazine. A related NHC catalyst 11 was utilized (Angew. Chem. Int. Ed. 2012, 51, 8276) by Xue-Wei Liu at Nanyang Technological University for the homoenolate addition of enal 9 to nitrodiene 10 to furnish 12 with high ee. The vinylogous conjugate addition of butenolide 13 to 15 to produce 16 with exquisite stereoselectivity was accomplished (Angew. Chem. Int. Ed. 2012, 51, 10069) by Kuo-Wei Huang at KAUST, Choon-Hong Tan at Henan University and Nanyang Technological University, and Zhiyong Jiang at Henan University. The enantioselective production of lactone 18 was achieved (J. Am. Chem. Soc. 2012, 134, 20197) by Jeffrey S. Johnson at the University of North Carolina at Chapel Hill by dynamic kinetic resolution (DKR) of α-keto ester 17. A related DKR strategy was employed (Org. Lett. 2012, 14, 6334) by Brinton Seashore-Ludlow at the KTH Royal Institute of Technology and Peter Somfai at Lund University in Sweden and the University of Tartu in Estonia for hydrogenation of α-amino-β-ketoester 19 to furnish aminoalcohol 21 with high Shigeki Matsunaga and Motomu Kanai at the University of Tokyo developed (Angew. Chem. Int. Ed. 2012, 51, 10275) a unique strategy for the selective production of the cross-aldol adduct 24 by in situ generation of an aldehyde enolate from allyloxyborane 23 under rhodium catalysis. The highly diastereoselective construction of adduct 26 bearing two adjacent quaternary stereocenters by ketone allylation with allyl sulfide 25 was reported (Angew. Chem. Int. Ed. 2012, 51, 7263) by Takeshi Takeda at the Tokyo University of Agriculture and Technology. Wen-Hao Hu at East China Normal University reported (Nature Chem. 2012, 4, 733) the enantioselective three-component coupling of diazoester 27, N-benzylindole (28), and imine 29 to furnish 31 under the action of Rh2(OAc)4 and phosphoric acid 30.

Author(s):  
Douglass Taber

Since five-membered ring ethers often do not show good selectivity on equilibration, single diastereomers are best formed under kinetic control. Aaron Aponick of the University of Florida demonstrated (Organic Lett. 2008, 10, 669) that under gold catalysis, the allylic alcohol 1 cyclized to 2 with remarkable diastereocontrol. Six-membered rings also formed with high cis stereocontrol. Ian Cumpstey of Stockholm University showed (Chem. Commun. 2008, 1246) that with protic acid, allylic acetates such as 3 cyclized with clean inversion at the allylic center, and concomitant debenzylation. J. Stephen Clark of the University of Glasgow found (J. Org. Chem. 2008, 73, 1040) that Rh catalyzed cyclization of 5 proceeded with high selectivity for insertion into Ha, leading to the alcohol 6. Saumen Hajra of the Indian Institute of Technology, Kharagpur took advantage (J. Org. Chem. 2008, 73, 3935) of the reactivity of the aldehyde of 7, effecting selective addition of 7 to 8, to deliver, after reduction, the lactone 9. Tomislav Rovis of Colorado State University observed (J. Org. Chem. 2008, 73, 612) that 10 could be cyclized selectively to either 11 or 12. Nadège Lubin-Germain, Jacques Uziel and Jacques Augé of the University of Cergy- Pontoise devised (Organic Lett. 2008, 10, 725) conditions for the indium-mediated coupling of glycosyl fluorides such as 13 with iodoalkynes such as 14 to give the axial C-glycoside 15. Katsukiyo Miura and Akira Hosomi of the University of Tsukuba employed (Chemistry Lett. 2008, 37, 270) Pt catalysis to effect in situ equilibration of the alkene 16 to the more stable regioisomer. Subsequent condensation with the aldehyde 17 led via Prins cyclization to the ether 18. Paul E. Floreancig of the University of Pittsburgh showed (Angew. Chem. Int. Ed. 2008, 47, 4184) that Prins cyclization could be also be initiated by oxidation of the benzyl ether 19 to the corresponding carbocation. Chan-Mo Yu of Sungkyunkwan University developed (Organic Lett. 2008, 10, 265) a stereocontrolled route to seven-membered ring ethers, by Pd-mediated stannylation of allenes such as 21, followed by condensation with an aldehyde.


Author(s):  
Douglass F. Taber

Varinder K. Aggarwal of the University of Bristol described (Angew. Chem. Int. Ed. 2010, 49, 6673) the conversion of the Sharpless-derived epoxide 1 into the cyclopropane 2. Christopher D. Bray of Queen Mary University of London established (Chem. Commun. 2010, 46, 5867) that the related conversion of 3 to 5 proceeded with high diastereocontrol. Javier Read de Alaniz of the University of California, Santa Barbara, extended (Angew. Chem. Int. Ed. 2010, 49, 9484) the Piancatelli rearrangement of a furyl carbinol 6 to allow inclusion of an amine 7, to give 8. Issa Yavari of Tarbiat Modares University described (Synlett 2010, 2293) the dimerization of 9 with an amine to give 10. Jeremy E. Wulff of the University of Victoria condensed (J. Org. Chem. 2010, 75, 6312) the dienone 11 with the commercial butadiene sulfone 12 to give the highly substituted cyclopentane 13. Robert M. Williams of Colorado State University showed (Tetrahedron Lett. 2010, 51, 6557) that the condensation of 14 with formaldehyde delivered the cyclopentanone 15 with high diastereocontrol. D. Srinivasa Reddy of Advinus Therapeutics devised (Tetrahedron Lett. 2010, 51, 5291) conditions for the tandem conjugate addition/intramolecular alkylation conversion of 16 to 17. Marie E. Krafft of Florida State University reported (Synlett 2010, 2583) a related intramolecular alkylation protocol. Takao Ikariya of the Tokyo Institute of Technology effected (J. Am. Chem. Soc. 2010, 132, 11414) the enantioselective Ru-mediated hydrogenation of bicyclic imides such as 18. This transformation worked equally well for three-, four-, five-, six-, and seven-membered rings. Stefan France of the Georgia Institute of Technology developed (Org. Lett. 2010, 12, 5684) a catalytic protocol for the homo-Nazarov rearrangement of the doubly activated cyclopropane 20 to the cyclohexanone 21. Richard P. Hsung of the University of Wisconsin effected (Org. Lett. 2010, 12, 5768) the highly diastereoselective rearrangement of the triene 22 to the cyclohexadiene 23. Strategies for polycyclic construction are also important. Sylvain Canesi of the Université de Québec devised (Org. Lett. 2010, 12, 4368) the oxidative cyclization of 24 to 25.


Author(s):  
Douglass F. Taber

Ramón Gómez Arrayás and Juan C. Carretero of the Universidad Autónoma de Madrid effected (Chem. Commun. 2011, 47, 6701) enantioselective conjugate borylation of an unsaturated sulfone 1, leading to the alcohol 2. Robert E. Gawley of the University of Arkansas found (J. Am. Chem. Soc. 2011, 133, 19680) conditions for enantioselective ketone reduction that were selective enough to distinguish between the ethyl and propyl groups of 3 to give 4. Vicente Gotor of the Universidad de Oviedo used (Angew. Chem. Int. Ed. 2011, 50, 8387) an overexpressed Baeyer-Villiger monoxygenase to prepare 6 by dynamic kinetic resolution of 5. Li Deng of Brandeis University prepared (J. Am. Chem. Soc. 2011, 133, 12458) 8 in high ee by kinetic enantioselective migration of the alkene of racemic 7. Bernhard Breit of the Freiburg Institute for Advanced Studies established (J. Am. Chem. Soc. 2011, 133, 20746) the oxygenated quaternary center of 10 by the addition of benzoic acid to the allene 9. Keith R. Fandrick of Boehringer Ingelheim constructed (J. Am. Chem. Soc. 2011, 133, 10332) the oxygenated quaternary center of 13 by enantioselective addition of the propargylic nucleophile 12 to 11. Yian Shi of Colorado State University devised (J. Am. Chem. Soc. 2011, 133, 12914) conditions for the enantioselective transamination of the α-keto ester 14 to the amine 15. Professor Deng added (Adv. Synth. Catal. 2011, 353, 3123) 18 to an enone 17 to give the protected amine 19. Song Ye of the Institute of Chemistry, Beijing effected (J. Am. Chem. Soc. 2011, 133, 15894) elimination/addition of an unsaturated acid chloride 20 to give the γ-amino acid derivative 22. Frank Glorius of the Universität Münster added (Angew. Chem. Int. Ed. 2011, 50, 1410) an aldehyde 23 to 24 to give the amide 25. Sentaro Okamoto of Kanagawa University designed (J. Org. Chem. 2011, 76, 6678) an organocatalyst for the enantioselective Steglich rearrangement of 26, creating the aminated quaternary center of 27. Most impressive of all was the report (Org. Lett. 2011, 13, 5460) by Hélène Lebel of the Université de Montréal of the direct enantioselective C–H amination of 28 to give 29.


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

Highly substituted dienes and dienophiles are often reluctant participants in intermolecular Diels-Alder cycloaddition. Nevertheless, Robert M. Williams of Colorado State University, in the course of a synthesis of fawcettimine 4, was able (J. Org. Chem. 2012, 77, 4801) to prepare 3 by combining the enone 1 with the diene 2. Günter Helmchen of the Universität Heidelberg set (J. Org. Chem. 2012, 77, 4491) the single stereogenic center of 5 by Ir-catalyzed allylic alkylation. The Lewis acid that promoted the cycloaddition also conveniently removed the trityl protecting group, leading to 6, that was saponified to apiosporic acid 7. Antonio Abad-Somovilla of the Universidad de Valencia prepared (J. Org. Chem. 2012, 77, 5664) the triene 8 in enantiomerically pure form from carvone. Despite the additional substitution on the diene, cycloaddition proceeded smoothly to give 9, which was carried on to marginatone 10. One could envision that okilactomycin 13 could be formed by an intramolecular Diels-Alder cycloaddition. Thomas R. Hoye of the University of Minnesota observed (Org. Lett. 2012, 14, 828) that the tetraene tetronic acid corresponding to 11 was inert, but that the methyl ether 11 cyclized smoothly to 12. Demethylation then gave the natural product The complex polycyclic structure of vinigrol 16 challenged organic synthesis chemists for many years, until a route was established by Phil Baran of Scripps/La Jolla (Highlights September 6, 2010). Louis Barriault cyclized (Angew. Chem. Int. Ed. 2012, 51, 2111) 14 to 15 en route to a late intermediate in the Baran synthesis It had been hypothesized that the natural product plakotenin 19 was formed naturally from a tetraene corresponding to 17. The tetraene 17 was prepared and the cyclization was successful, “confirming” both the structure of the natural product and the biosynthetic hypothesis. Angela Bihlmeier and Wim Klopper of the Karlsruhe Institute of Technology calculated (J. Am. Chem. Soc. 2012, 134, 2154) the relative energies of the four competing transition states for the cyclization, leading to a correction of the structure of 18, and so of the natural product 19.


Author(s):  
Douglass F. Taber

John F. Hartwig of the University of California, Berkeley effected (J. Am. Chem. Soc. 2013, 135, 3375) selective borylation of the cyclopropane 1 to give 2. It would be particularly useful if this borylation could be made enantioselective. Eric M. Ferreira of Colorado State University showed (Org. Lett. 2013, 15, 1772) that the enantomeric excess of 3 was transferred to the highly substituted cyclopropane 4. Antonio M. Echavarren of ICIQ Tarragona demonstrated (Org. Lett. 2013, 15, 1576) that Au-mediated cyclobutene construction could be used to form the medium ring of 6. Joseph M. Fox of the University of Delaware developed (J. Am. Chem. Soc. 2013, 135, 9283) what promises to be a general enantioselective route to cyclobutanes such as 8 by way of the intermediate bicyclobutane (not illustrated). Huw M.L. Davies of Emory University reported (Org. Lett. 2013, 15, 310) a preliminary investigation in this same direction. Masahisa Nakada of Waseda University prepared (Org. Lett. 2013, 15, 1004) the cyclopentane 10 by enantioselective cyclization of 9 followed by reductive opening. Young-Ger Suh of Seoul National University cyclized (Org. Lett. 2013, 15, 531) the lactone 11 to the cyclopentane 12. Xavier Ariza and Jaume Farràs of the Universitat de Barcelona optimized (J. Org. Chem. 2013, 78, 5482) the Ti-mediated reductive cyclization of 13 to 14. The hydrogenation catalyst reduced the intermediate Ti–C bond without affecting the alkene. Erick M. Carreira of ETH Zürich observed (Angew. Chem. Int. Ed. 2013, 52, 5382) that a sterically demanding Rh catalyst mediated the highly diastereoselective cyclization of 15 to 16. The ketone 16 was the key intermediate in a synthesis of the epoxyisoprostanes. Jianrong (Steve) Zhou of Nanyang Technological University used (Angew. Chem. Int. Ed. 2013, 52, 4906) a Pd catalyst to effect the coupling of 17 with the prochiral 18. Geum-Sook Hwang and Do Hyun Ryu of Sungkyunkwan University devised (J. Am. Chem. Soc. 2013, 135, 7126) a boron catalyst to effect the addition of the diazo ester 21 to 20. They showed that the sidechain stereocenter was effective in directing the subsequent hydrogenation of 22.


Author(s):  
Douglass Taber

Armando Córdova of Stockholm University has found (Tetrahedron Lett. 2008, 49, 4209) that the organocatalyst 3a effected enantioselective conjugate addition of bromonitromethane 2 to the α,β-unsaturated aldehyde 1, to give the cyclopropane 4 as a ~ 1:1 diastereomeric mixture, both in high ee. Tomislav Rovis of Colorado State University has published (J. Org. Chem. 2008, 73, 2033) a detailed account of his development of catalysts such as 6, that effected enantioselective cyclization of 5 to 7 with excellent ee. Karl Anker Jørgensen of Aarhus University has employed (J. Am. Chem. Soc. 2008, 130, 4897) chiral quaternary salts derived from quinine that mediated the enantioselective addition of prochiral rings such as 8 to the allenoate ester 9 to give 10 with high ee. Organocatalysts have also been used to prepare more highly substituted cyclohexane derivatives. Guofu Zhong of Nanyang Technological University used (Organic Lett. 2008, 10, 2437) a quinine-derived secondary amine to catalyze the Michael addition of 12 to 11 followed by intramolecular aldol (Henry) reaction, to give 13. When Professor Jørgensen attempted (Angew. Chem. Int. Ed. 2008, 47, 121) the related addition of 14 and 15 using catalyst 3a, he did not observe the expected Michael-Michael sequence. Rather, the initial Michael addition was followed by a Morita-Baylis-Hillman condensation, to give 16. The β-keto ester 16 existed primarily in its enol form. Organocatalysts can also be used to prepare polycyclic systems. Professor Jørgensen has found (Chem. Commun. 2008, 3016) that condensation of 14 with acetone dicarboxylate 17, again using catalyst 3a, gave the bicyclic β-keto ester 18. Matthew J. Gaunt of the University of Cambridge observed (J. Am. Chem. Soc. 2008, 130, 404) that for the cyclization of 19, catalyst 3b was superior to catalyst 3a. The power of desymmetrization of prochiral intermediates was illustrated by the report (J. Am. Chem. Soc. 2008, 130, 6737) from Benjamin List of the Max-Planck-Institute, Mülheim of the cyclization of 21 to 23. Organocatalysts can also be used to prepare larger rings.


Author(s):  
Douglass F. Taber

Akio Saito and Yuji Hanzawa of Showa Pharmaceutical University found (Tetrahedron Lett. 2011, 52, 4658) that an alkynyl keto ester 1 could be oxidatively cyclized to the furan 2. Eric M. Ferreira of Colorado State University showed (Org. Lett. 2011, 13, 5924) that depending on the conditions, a Pt catalyst could cyclize 3 to either 4 or 5. Shunsuke Chiba of Nanyang Technological University used (J. Am. Chem. Soc. 2011, 133, 13942) Cu catalysis for the oxidation of 6 to the pyrrole 7. Vladimir Gevorgyan of the University of Illinois at Chicago devised (Org. Lett. 2011, 13, 3746) a convergent assembly of the pyrrole 10 from the alkyne 8 and the alkyne 9. Dale L. Boger of Scripps La Jolla extended (J. Am. Chem. Soc. 2011, 133, 12285) the scope of the Diels-Alder addition of the triazine 11 to an alkyne 12 to give the pyridine 13. Tomislav Rovis, also of Colorado State University, used (Chem. Commun. 2011, 47, 11846) a Rh catalyst to add an alkyne 15 to the oxime 14 to give the pyridine 16. Sensuke Ogoshi of Osaka University, under Ni catalysis, added (J. Am. Chem. Soc. 2011, 133, 18018) a nitrile 18 to the diene 17 to give the pyridine 19. Alexander Deiters of North Carolina State University showed (Org. Lett. 2011, 13, 4352) that the complex tethered diyne 20 combined with 21 with high regiocontrol to give 22. Yong-Min Liang of Lanzhou University prepared (J. Org. Chem. 2011, 76, 8329) the indole 24 by cyclizing the alkyne 23. Xiuxiang Qi and Kang Zhao of Tianjin University found (J. Org. Chem. 2011, 76, 8690) that the enamine 25 could be oxidatively cyclized to the indole 26. Kazuhiro Yoshida and Akira Yanagisawa of Chiba University established (Org. Lett. 2011, 13, 4762) that ring-closing metathesis converted the keto ester 27 to the indole 28. Alessandro Palmieri and Roberto Ballini of the Università di Camerino observed (Adv. Synth. Catal. 2011, 353, 1425) that the pyrrole 30 spontaneously added to the nitro acrylate 29 to give an adduct that cyclized to 31 on exposure to acid.


2019 ◽  
Vol 10 (2) ◽  
Author(s):  
George Lorenzo

Nine institutions—Colorado State University, Dallas County Community College District (DCCCD), Duquesne University, Georgia Institute of Technology, University of Central Florida, The University of Illinois at Springfield, University of Massachusetts Lowell, University of Michigan, University of Georgia—share information about their business models.


Synlett ◽  
2021 ◽  
Vol 32 (02) ◽  
pp. 140-141
Author(s):  
Louis-Charles Campeau ◽  
Tomislav Rovis

obtained his PhD degree in 2008 with the late Professor Keith Fagnou at the University of Ottawa in Canada as an NSERC Doctoral Fellow. He then joined Merck Research Laboratories at Merck-Frosst in Montreal in 2007, making key contributions to the discovery of Doravirine (MK-1439) for which he received a Merck Special Achievement Award. In 2010, he moved from Quebec to New Jersey, where he has served in roles of increasing responsibility with Merck ever since. L.-C. is currently Executive Director and the Head of Process Chemistry and Discovery Process Chemistry organizations, leading a team of smart creative scientists developing innovative chemistry solutions in support of all discovery, pre-clinical and clinical active pharmaceutical ingredient deliveries for the entire Merck portfolio for small-molecule therapeutics. Over his tenure at Merck, L.-C. and his team have made important contributions to >40 clinical candidates and 4 commercial products to date. Tom Rovis was born in Zagreb in former Yugoslavia but was largely raised in southern Ontario, Canada. He earned his PhD degree at the University of Toronto (Canada) in 1998 under the direction of Professor Mark Lautens. From 1998–2000, he was an NSERC Postdoctoral Fellow at Harvard University (USA) with Professor David A. Evans. In 2000, he began his independent career at Colorado State University and was promoted in 2005 to Associate Professor and in 2008 to Professor. His group’s accomplishments have been recognized by a number of awards including an Arthur C. Cope Scholar, an NSF CAREER Award, a Fellow of the American Association for the Advancement of Science and a ­Katritzky Young Investigator in Heterocyclic Chemistry. In 2016, he moved to Columbia University where he is currently the Samuel Latham Mitchill Professor of Chemistry.


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