Alkenes

2017 ◽  
Author(s):  
Allison K. Griffith ◽  
Tristan H. Lambert
Keyword(s):  
State University ◽  
One Pot ◽  
Colorado State University ◽  
University Of Oxford ◽  
University Of British Columbia ◽  
University Of Wisconsin ◽  
Unsaturated Carbonyl Compound ◽  
Institute Of Technology ◽  
University Of Zurich ◽  
The University

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.

Other Methods for Carbocyclic Construction: The Porco Synthesis of (-)-Hyperibone K

2013 ◽  
Author(s):  
Douglass F. Taber
Keyword(s):  
Oxidative Cyclization ◽  
Florida State University ◽  
State University ◽  
Colorado State University ◽  
Intramolecular Alkylation ◽  
University Of Wisconsin ◽  
Tokyo Institute ◽  
Institute Of Technology ◽  
University Of Bristol ◽  
The University

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.

Stereocontrolled C-O Ring Construction: The Fuwa/Sasaki Synthesis of Attenol A

2011 ◽  
Author(s):  
Douglass Taber
Keyword(s):  
Gold Catalysis ◽  
Membered Ring ◽  
Allylic Alcohol ◽  
State University ◽  
Prins Cyclization ◽  
University Of Florida ◽  
University Of Pittsburgh ◽  
Colorado State University ◽  
Institute Of Technology ◽  
The University

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.

C–O Natural Products: (–)-Hybridalactone (Fürstner), (+)-Anthecotulide (Hodgson), (–)-Kumausallene (Tang), (±)-Communiol E (Kobayashi), (–)-Exiguolide (Scheidt), Cyanolide A (Rychnovsky)

2015 ◽  
Author(s):  
Douglass F. Taber
Keyword(s):  
Max Planck ◽  
Enantiomerically Pure ◽  
University Of Oxford ◽  
University Of Wisconsin ◽  
Favorskii Rearrangement ◽  
Alternative Approach ◽  
Ether Oxygen ◽  
Institute Of Technology ◽  
The University ◽  
Complementary Strategy

Control of the absolute configuration of adjacent alkylated stereogenic centers is a classic challenge in organic synthesis. In the course of the synthesis of (–)-hybridalactone 4, Alois Fürstner of the Max-Planck-Institut Mülheim effected (J. Am. Chem. Soc. 2011, 133, 13471) catalytic enantioselective conjugate addition to the simple acceptor 1. The initial adduct, formed in 80% ee, could readily be recrystallized to high ee. In an alternative approach to high ee 2,3-dialkyl γ-lactones, David M. Hodgson of the University of Oxford cyclized (Org. Lett. 2011, 13, 5751) the alkyne 5 to an aldehyde, which was condensed with 6 to give 7. Coupling with 8 then delivered (+)-anthecotulide 9. The enantiomerically pure diol 10 is readily available from acetylacetone. Weiping Tang of the University of Wisconsin dissolved (Org. Lett. 2011, 13, 3664) the symmetry of 10 by Pd-mediated cyclocarbonylation. The conversion of the lactone 11 to (–)-kumausallene 12 was enabled by an elegant intramolecular bromoetherification. Shoji Kobayshi of the Osaka Institute of Technology developed (J. Org. Chem. 2011, 76, 7096) a powerful oxy-Favorskii rearrangement that enabled the preparation of both four-and five-membered rings with good diastereocontrol, as exemplified by the conversion of 13 to 14. With the electron-withdrawing ether oxygen adjacent to the ester carbonyl, Dibal reduction of 14 proceeded cleanly to the aldehyde. Addition of ethyl lithium followed by deprotection completed the synthesis of (±)-communiol E. En route to (–)-exiguolide 18, Karl A. Scheidt of Northwestern University showed (Angew. Chem. Int. Ed. 2011, 50, 9112) that 16 could be cyclized efficiently to 17. The cyclization may be assisted by a scaffolding effect from the dioxinone ring. Dimeric macrolides such as cyanolide A 21 are usually prepared by lactonization of the corresponding hydroxy acid. Scott D. Rychnovsky of the University of California Irvine devised (J. Am. Chem. Soc. 2011, 133, 9727) a complementary strategy, the double Sakurai dimerization of the silyl acetal 19 to 20.

Heteroaromatic Synthesis: The Tokuyama Synthesis of (−)-Rhazinilam

2017 ◽  
Author(s):  
Douglass F. Taber
Keyword(s):  
Ni Catalyst ◽  
State University ◽  
Colorado State University ◽  
Ru Catalyst ◽  
Opioid Ligands ◽  
University Of Wisconsin ◽  
Rh Catalyst ◽  
Indian Institute Of Science ◽  
The University ◽  
École Polytechnique

Mei-Huey Lin of the National Changhua University of Education rearranged (J. Org. Chem. 2014, 79, 2751) the initial allene derived from 1 to the γ-chloroenone. Displacement with acetate followed by hydrolysis led to the furan 2. A. Stephen K. Hashmi of Ruprecht-Karls-Universität Heidelberg showed (Angew. Chem. Int. Ed. 2014, 53, 3715) that the Au-catalyzed conversion of the bis alkyne 3, mediated by 4, proceeded selectively to give 5. Tehshik P. Yoon of the University of Wisconsin used (Angew. Chem. Int. Ed. 2014, 53, 793) visible light with a Ru catalyst to rearrange the azide 6 to the pyrrole 7. Cheol-Min Park, now at UNIST, found (Chem. Sci. 2014, 5, 2347) that a Ni catalyst reorganized the methoxime 8 to the pyrrole 9. A Rh catalyst converted 8 to the corresponding pyridine (not illustrated). In the course of a synthesis of opioid ligands, Kenner C. Rice of the National Institute on Drug Abuse optimized (J. Org. Chem. 2014, 79, 5007) the preparation of the pyridine 11 from the alcohol 10. Vincent Tognetti and Cyrille Sabot of the University of Rouen heated (J. Org. Chem. 2014, 79, 1303) 12 and 13 under micro­wave irradiation to give the 3-hydroxy pyridine 14. Tomislav Rovis of Colorado State University prepared (J. Am. Chem. Soc. 2014, 136, 2735) the pyridine 17 by the Rh-catalyzed combination of 15 with 16. Fabien Gagosz of the Ecole Polytechnique rearranged (Angew. Chem. Int. Ed. 2014, 53, 4959) the azirine 18, readily available from the oxime of the β-keto ester, to the pyridine 19. Matthias Beller of the Universität Rostock used (Chem. Eur. J. 2014, 20, 1818) a Zn catalyst to mediate the opening of the epoxide 21 with the aniline 20. A Rh cata­lyst effected the oxidation and cyclization of the product amino alcohol to the indole 22. Sreenivas Katukojvala of the Indian Institute of Science Education & Research showed (Angew. Chem. Int. Ed. 2014, 53, 4076) that the diazo ketone 23 could be used to anneal a benzene ring onto the pyrrole 24, leading to the 2,7-disubstituted indole 25.

New Methods for C–N Ring Construction

2015 ◽  
Author(s):  
Tristan H. Lambert
Keyword(s):  
New York ◽  
Gold Catalyst ◽  
Earth Metal ◽  
Allylic Alcohols ◽  
State University ◽  
University Of Oxford ◽  
University Of Wisconsin ◽  
Vinyl Iodide ◽  
Hydride Elimination ◽  
The University

The reduction of pyridines offers an attractive approach to piperidine synthesis, and now Toshimichi Ohmura and Michinori Suginome of Kyoto University have developed (J. Am. Chem. Soc. 2012, 134, 3699) a rhodium-catalyzed hydroboration of pyridines, including the reaction of 1 to produce 3. Timothy J. Donohoe at the University of Oxford has found (Org. Lett. 2011, 13, 2074) that pyridinium silanes 4 undergo intramolecular hydride transfer by treatment with TBAF to produce dihydropyridones (e.g., 5) with good diastereoselectivity. Enantioselective amination of allylic alcohols has proven challenging, but Ross A. Widenhoefer at Duke University has reported (Angew. Chem. Int. Ed. 2012, 51, 1405) that a chiral gold catalyst can effect such intramolecular cyclizations with good enantioselectivity, as in the synthesis of 7 from 6. Alternatively, Masato Kitamura at Nagoya University has developed (Org. Lett. 2012, 14, 608) a ruthenium catalyst that operates at as low as 0.05 mol% loading for the conversion of substrates such as 8 to 9. Efforts to replace transition metal catalysts with alkaline earth metal-based alternatives have been gaining increasing attention, and Kai C. Hultzsch at Rutgers University has found (Angew. Chem. Int. Ed. 2012, 51, 394) that the magnesium complex 12 is capable of catalyzing intramolecular hydroamination (e.g., 10 to 11) with high enantioselectivity. Meanwhile, a stereoselective Wacker-type oxidation of tert-butanesulfinamides such as 13 to produce pyrrolidine derivatives 14 has been disclosed (Org. Lett. 2012, 14, 1242) by Shannon S. Stahl at the University of Wisconsin at Madison. Though highly desirable, Heck reactions have rarely proven feasible with alkyl halides due to competitive β-hydride elimination of the alkyl palladium intermediates. Sherry R. Chemler at the State University of New York at Buffalo has demonstrated (J. Am. Chem. Soc. 2012, 134, 2020) a copper-catalyzed enantioselective amination Heck-type cascade (e.g., 15 and 16 to 17) that is thought to proceed via radical intermediates. David L. Van Vranken at the University of California at Irvine has reported (Org. Lett. 2012, 14, 3233) the carbenylative amination of N-tosylhydrazones, which proceeds through η3-allyl Pd intermediates constructed via carbene insertion. This chemistry was applied to the two-step synthesis of caulophyllumine B from vinyl iodide 18 and N-tosylhydrazone 19.

Diels-Alder Cycloaddition: Fawcettimine (Williams), Apiosporic Acid (Helmchen), Marginatone (Abad- Somovilla), Okilactomycin (Hoye), Vinigrol (Barriault), Plakotenin (Bihlmeier/Klopper)

2015 ◽  
Author(s):  
Douglass F. Taber
Keyword(s):  
Natural Product ◽  
Diels Alder ◽  
State University ◽  
University Of Minnesota ◽  
Enantiomerically Pure ◽  
Colorado State University ◽  
Institute Of Technology ◽  
La Jolla ◽  
The University ◽  
Stereogenic Center

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.

C–N Ring Construction: The Hoye Synthesis of (±)-Leuconolactam

2015 ◽  
Author(s):  
Douglass F. Taber
Keyword(s):  
British Columbia ◽  
Indian Institute ◽  
South Florida ◽  
Chiral Auxiliary ◽  
Dipolar Cycloaddition ◽  
University Of Oxford ◽  
University Of British Columbia ◽  
Memory Of Chirality ◽  
Institute Of Technology ◽  
The University

Manas K. Ghorai of the Indian Institute of Technology, Kanpur depended (J. Org. Chem. 2013, 78, 2311) on memory of chirality during deprotonation to convert 1 to the aziridine 3. X. Peter Zhang of the University of South Florida demonstrated (Angew. Chem. Int. Ed. 2013, 52, 5309) that Co-catalyzed enantioselective aziridination is compatible with fluoro-aromatics such as 5. David M. Hodgson of the University of Oxford prepared (J. Org. Chem. 2013, 78, 1098) the azetidine 8 by double deprotonation of 7 followed by acylation. Laurel L. Schafer of the University of British Columbia assembled (Org. Lett. 2013, 15, 2182) 11 by Ta-catalyzed aminoalkylation of 10 with 9, followed by cyclization. Nicholas A. Magnus of Eli Lilly reduced (J. Org. Chem. 2013, 78, 5768) the ketone 12 to the alcohol 13 with high de and ee. Pei-Qiang Huang of Xiamen University effected (J. Org. Chem. 2013, 78, 1790) the reductive addition of 14 to 15 to give 16. The titanocene protocol reported (Angew. Chem. Int. Ed. 2013, 52, 3494) by Xiao Zheng, also of Xiamen University, effectively mediated similar transformations. En route to (–)-quinocarcin, Nobutaka Fujii and Hiroaki Ohno of Kyoto University cyclized (Chem. Eur. J. 2013, 19, 8875) 17 to 18 with high diastereoselectivity. Dipolar cycloaddition, long a workhorse of pyrrolidine synthesis, has been improved by enantioselective organocatalysis. For instance, Liu-Zhu Gong of the University of Science and Technology of China combined (Org. Lett. 2013, 15, 2676) 19, 20, and 21 to give the triester 22. Qi-Lin Zhou of Nankai University reduced (Angew. Chem. Int. Ed. 2013, 52, 6072) the tetrahydropyridine 23 to 24 in high ee. Takaaki Sato and Noritaka Chida of Keio University cyclized (Chem. Eur. J. 2013, 19, 678) the intermediate from reduction of 25 to the piperidine 26. Yasumasa Hamada of Chiba University devised (Tetrahedron Lett. 2013, 54, 1562) the rearrangement of 27 to the piperidine 28. In a synthesis of (–)-hippodamine, Shigeo Katsumura of Kwansei Gakuin University used (Org. Lett. 2013, 15, 2758) the chiral auxiliary 29 to direct the combination of 30 with 31 to give 32.

Construction of Alkenes, Alkynes and Allenes

2011 ◽  
Author(s):  
Douglass Taber
Keyword(s):  
Cation Exchange Resin ◽  
Terminal Alkyne ◽  
Amberlyst 15 ◽  
University Of Oxford ◽  
University Of British Columbia ◽  
University Of Louisville ◽  
Rh Catalyst ◽  
Institute Of Technology ◽  
The University ◽  
Trisubstituted Alkenes

Products such as 3 and 6 are usually prepared by phosphonate condensation. J. S. Yadav of the Indian Institute of Technology, Hyderabad found (Tetrahedron Lett. 2008, 49, 4498) that the cation-exchange resin Amberlyst-15 in CH2Cl2 mediated the condensation of a terminal alkyne such as 1 with an aldehyde to give the enone 3. Similarly, Teruaki Mukaiyama of Kitasato University showed (Chemistry Lett. 2008, 37, 704) that tetrabutylammonium acetate mediated the condensation of 5 with an aldehyde such as 4 to give the ester 6. David M. Hodgson of the University of Oxford described (J. Am. Chem. Soc. 2008, 130, 16500) the optimization of the Schlosser protocol for the condensation of a phosphorane with an aldehyde 7 followed by deprotonation and halogenation, to deliver the alkenyl halide 9 with good geometric control. Jun Terao of Kyoyo University and Nobuaki Kambe of Osaka University accomplished (Chem. Commun. 2008, 5836) the homologation of a halide such as 10 to the corresponding allylic Grignard reagent 12. Primary, secondary and tertiary halides worked well. Jennifer Love of the University of British Columbia developed (Organic Lett. 2008, 10, 3941) a Rh catalyst for the addition of thiols to terminal alkynes such as 13, and found that the product thioether 14 coupled smoothly with Grignard reagents to deliver the 1,1-disubstituted alkene 15. Glenn C. Micalizio, now at Scripps Florida, established (J. Am. Chem. Soc. 2008, 130, 16870) what appears to be a general method for the construction of Z-trisubstituted alkenes such as 18. The Ohira protocol has become the method of choice for converting an aldehyde 19 to the alkyne 21. We have found (Tetrahedron Lett. 2008, 49, 6904) that the reagent 20 offers advantages in price, preparation and handling. Bo Xu and Gerald B. Hammond of the University of Louisville observed (Organic Lett. 2008, 10, 3713) that an allene ester such as 22 is readily homologated to the alkyne 23. Ashton C. Partridge of Massey University extended (Tetrahedron Lett. 2008, 49, 5632) condensation with the aryl phosphonate 25 to porphyrin aldehydes, leading to alkynes such as 26.

Construction of Stereochemical Arrays

2015 ◽  
Author(s):  
Tristan H. Lambert
Keyword(s):  
Kinetic Resolution ◽  
Alder Reaction ◽  
State University ◽  
Rhodium Catalysis ◽  
Colorado State University ◽  
Allyl Sulfide ◽  
Institute Of Technology ◽  
Quaternary Stereocenters ◽  
The University ◽  
Technological University

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.

C-N Ring Construction: The Zakarian Synthesis of (-)-Rhazinilam

2013 ◽  
Author(s):  
Douglass F. Taber
Keyword(s):  
New York ◽  
Claisen Rearrangement ◽  
Michigan State University ◽  
State University ◽  
University Of Michigan ◽  
University Of Alberta ◽  
University Of British Columbia ◽  
Complementary Approach ◽  
Institute Of Technology ◽  
The University

William D. Wulff of Michigan State University developed (J. Am. Chem. Soc. 2010, 132, 13100; Org. Lett. 2010, 12, 4908) a general enantio- and diastereocontrolled route from an imine 1 to the aziridine 3. Craig W. Lindsley of Vanderbilt University established (Org. Lett. 2010, 12, 3276) a complementary approach (not illustrated). Joseph P. Konopelski of the University of California, Santa Cruz, designed (J. Am. Chem. Soc. 2010, 132, 11379) a practical and inexpensive flow apparatus for the cyclization of 4 to the β-lactam 5. Manas K. Ghorai of the Indian Institute of Technology, Kanpur, showed (J. Org. Chem. 2010, 75, 6173) that an aziridine 6 could be opened with malonate to give the γ-lactam 8. John P. Wolfe of the University of Michigan devised (J. Am. Chem. Soc. 2010, 132, 12157) a Pd catalyst for the enantioselective cyclization of 9 to 11. Sherry R. Chemler of the State University of New York at Buffalo observed (Angew. Chem. Int. Ed. 2010, 49, 6365) that the cyclization of 12 to 14 proceeded with high diastereoselectivity. Glenn M. Sammis of the University of British Columbia devised (Synlett 2010, 3035) conditions for the radical cyclization of 15 to 16. Jeffrey S. Johnson of the University of North Carolina observed (J. Am. Chem. Soc. 2010, 132, 9688) that the opening of racemic 17 with 18 could be effected with high ee. The residual 17 was highly enriched in the nonreactive enantiomer. Kevin D. Moeller of Washington University found (Org. Lett . 2010, 12, 5174) that the n -BuLi catalyzed cyclization of 20 set the quaternary center of 21 with high relative control. Yujiro Hayashi of the Tokyo University of Science, using the diphenyl prolinol TMS ether that he developed as an organocatalyst, designed (Org. Lett. 2010, 12, 4588) the sequential four-component coupling of 22, 23, benzaldehyde imine, and allyl silane to give 24 with high relative and absolute stereocontrol. Derrick L. J. Clive of the University of Alberta showed (J. Org. Chem. 2010, 75, 5223) that 25, prepared in enantiomerically pure form from serine, participated smoothly in the Claisen rearrangement, to deliver 27.

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