Arrays of Stereogenic Centers: The Thomson Synthesis of (−)-Galactin

2017 ◽  
Author(s):  
Douglass F. Taber
Keyword(s):  
East China ◽  
Allylic Alcohols ◽  
University Of Texas ◽  
University Of New Mexico ◽  
Homoallylic Alcohols ◽  
Stereogenic Centers ◽  
Normal University ◽  
The University ◽  
Medical University

Hisashi Yamamoto of the University of Chicago and Chubu University developed (J. Am. Chem. Soc. 2014, 136, 1222) a tungsten catalyst for the enantioselective oxida­tion of allylic alcohols such as 1 to the epoxide 2. Homoallylic alcohols also worked well. Naoya Kumagai and Masakatsu Shibasaki of the Institute of Microbial Chemistry devised (Chem. Eur. J. 2014, 20, 68) a scalable Zn-catalyzed protocol for the coupling of 3 with 4 to give 5. Professor Shibasaki and Takumi Watanabe, also of the Institute of Microbial Chemistry, established (Org. Lett. 2014, 16, 3364) a Nb catalyst for the preparation of 8 by the Henry addition of 7 to 6. Wenhao Hu of East China Normal University effected (Synthesis 2014, 46, 1348) the coupling of 9 and 10 with two equivalents of aniline to give the diamine 10. Sanzhong Luo of the Institute of Chemistry, Beijing showed (Angew. Chem. Int. Ed. 2014, 53, 4149) that the adduct between 11 and an in situ formed N-nitroso could be reduced with high diastereoselectivity, leading to 12. Kumagai and Shibasaki also described (Angew. Chem. Int. Ed. 2014, 53, 5327) the assembly of 15 by the enantiose­lective addition 14 to 13. Bernhard Breit of the Albert-Ludwigs-Universität Freiburg effected (Synthesis 2014, 46, 1311) the carbonylation of the alkene 16 to give an alde­hyde that underwent in situ condensation with the imine 17, leading, after a subse­quent addition of vinyl magnesium chloride, to the lactone 18. Michael J. Krische of the University of Texas prepared (J. Am. Chem. Soc. 2014, 136, 8911) the diol 21 by adding the racemic epoxide 20 to the aldehyde 19. Martin Hiersemann of the Technische Universität Dortmund achieved (J. Org. Chem. 2014, 79, 3040) high enantioselectivity in the rearrangement of the enol ether 22 to 23. Michael T. Crimmins also observed (Org. Lett. 2014, 16, 2458) high ste­reocontrol in the rearrangement of 24 to 25. Wannian Zhang and Chunquan Sheng of the Second Military Medical University and Wei Wang of the University of New Mexico and the East China University of Science and Technology added (Org. Lett. 2014, 16, 692) the diketone 26 to the aldehyde 6 to give an intermediate adduct, that further cyclized to 27.

Stereocontrolled Construction of Arrays of Stereogenic Centers

2011 ◽  
Author(s):  
Douglass Taber
Keyword(s):  
Aldol Condensation ◽  
University Of Minnesota ◽  
Chiral Amine ◽  
University Of Texas ◽  
Crotyl Alcohol ◽  
Alternative Approach ◽  
Stereogenic Centers ◽  
La Jolla ◽  
The University

The Sharpless osmium-catalyzed asymmetric dihydroxylation is widely used. Lawrence Que, Jr. of the University of Minnesota designed (Angew. Chem. Int. Ed. 2008, 47, 1887) a catalyst with the inexpensive Fe that appears to be at least as effective, converting 1 to 2 in high ee. In an alternative approach, Bernd Plietker of the Universität Stuttgart used (J. Org. Chem. 2008, 73, 3218) chiral auxiliary control to direct dihydroxylation. The diastereomers of 4 were readily differentiated. Defined arrays of stereogenic centers can also be constructed by homologation. Armando Córdova of Stockholm University condensed (Tetrahedron Lett. 2008, 49, 803) dihydroxy acetone 6 with an in situ generated imine 5 to give the amino diol 8. In parallel work, Carlos F. Barbas III of Scripps/La Jolla described (Organic Lett. 2008, 10, 1621) a related addition to aldehydes. Magnus Rueping of University Frankfurt found (Organic Lett. 2008, 10, 1731) conditions for the addition of a nitro alkane such as 9 to the imine 10 to give 11. Keiji Maruoka of Kyoto University devised (J. Am. Chem. Soc. 2008, 130, 3728) a chiral amine that mediated the enantioselective iodination of aldehydes such as 12. Direct cyanohydrin formation delivered 13 in high de and ee. The epoxide 14 is readily prepared in high ee from crotyl alcohol. Barry M. Trost of Stanford University found (Organic Lett. 2008, 10, 1893) that 14 could be opened with 15, to give 16 with high regio- and diastereocontrol. Jérôme Blanchet of the Université de Caen Basse-Normandie optimized (Organic Lett. 2008, 10 , 1029) the amine 19 as a catalyst for the condensation of ketones such as 17 with the imine 18, to give 20. Michael J. Krische of the University of Texas has explored (J. Am. Chem. Soc. 2008, 130, 2746) the in situ generation of chiral Rh enolates from enones such as 21, and the subsequent aldol condensation with aldehydes such as 22. Shu Kobayashi of the University of Tokyo found (Organic Lett. 2008, 10, 807) that the conjugate addition of 25 to 24 mediated by a chiral Ca catalyst proceeded with high enantiocontrol at both of the newly formed stereogenic centers, to give 26.

Enantioselective Construction of Alkylated Centers: The Maier Synthesis of Platencin

2013 ◽  
Author(s):  
Douglass F. Taber
Keyword(s):  
Conjugate Addition ◽  
Unsaturated Ketone ◽  
West Virginia University ◽  
Aryl Iodide ◽  
Quaternary Centers ◽  
University Of New Mexico ◽  
Conjugate Reduction ◽  
Complementary Approach ◽  
Stereogenic Centers ◽  
The University

Jaesook Yun of Sungkyunkwan University devised (J. Org. Chem. 2009, 74, 4232) a method, based on conjugate addition to a cyano alkyne, for the preparation of nitriles such as 1 with high geometric control. Enantioselective conjugate reduction then delivered the doubly arylated stereogenic center of 2 in high ee. Pher G. Andersson of Uppsala University described (J. Am. Chem. Soc. 2009, 131, 8855) a similar approach to diarylated ternary stereogenic centers. Motomu Kanai and Masakatsu Shibasaki of the University of Tokyo developed (J. Am. Chem. Soc. 2009, 131, 3858) a complementary approach to dialkylated stereogenic centers based on enantioselective conjugate cyanation of α-methylene N-acylpyrroles such as 3. Cathleen M. Crudden of Queen’s University established (J. Am. Chem. Soc. 2009, 131, 5024) that a benzylic organoborane, prepared by enantioselective hydroboration of styrene, coupled with an aryl iodide such as 6 in good yield and with > 90% retention of ee. Kwunmin Chen of National Taiwan Normal University devised ( Adv. Synth. Cat. 2009, 351, 1273) an organocatalyst for the enantioselective Michael addition of an α,α,-dialkyl aldehyde such as 9 to a nitroalkene. Wenhu Duan of the East China University of Science and Technology and Wei Wang of the University of New Mexico together developed (Organic Lett. 2009, 11, 2864) an organocatalyst for the enantioselective addition of nitromethane 12 to an unsaturated ketone such as 11. Xiaodong Shi of West Virginia University found (Angew. Chem. Int. Ed. 2009, 48, 1279) that commercial diphenyl prolinol effectively promoted enantioselective conjugate addition of 15 to 14. Enantioselective methods for the construction of alkylated quaternary centers have also been put forward. Kin-ichi Tadano of Keio University devised (Tetrahedron Lett. 2009, 50, 1139) a glucose-derived chiral auxiliary that effectively directed the absolute sense of the alkylation of 17. Li Deng of Brandeis University reported (Tetrahedron 2009, 65, 3139) further details of his elegant Cinchona -mediated conjugate addition of 19 to 20. Francesca Marini of the Università degli Studi di Perugia extended (Adv. Synth. Cat. 2009, 351, 103) this approach to selenones, effecting, over two steps, enantioselective vinylation.

HREM study of phase transformation induced by ion irradiation in Al-Cu-Co-Ge single decagonal quasicrystal

1996 ◽  
Vol 54 ◽  
pp. 722-723
Author(s):  
L.F. Chen ◽  
L.M. Wang ◽  
R.C. Ewing
Keyword(s):  
Phase Transformation ◽  
Ion Irradiation ◽  
National Laboratory ◽  
Research Field ◽  
In Situ Tem ◽  
Decagonal Quasicrystal ◽  
University Of New Mexico ◽  
Fundamental Understanding ◽  
The University

Irradiation-induced phase transformation in crystals has been an interesting research field for the past twenty years. Since the discovery of quasicrystals in Al-based alloys, there have been some reports on irradiation-induced phase transformation in quasicrystals by in situ TEM observations. However, detailed study on phase transformation in quasicrystals under ion irradiation at atomic level using HREM is necessary for the fundamental understanding of the process. In this paper, we report the results from a systematic HREM study on phase transformation induced by ion irradiation in Al-Cu-Co-Ge single decagonal quasicrystal (31.4 wt.% Cu, 21.8 wt.% Co and 5.4 wt.% Ge).The TEM specimens of single decagonal quasicrystal were prepared perpendicular to the tenfold axis. The transformation in single quasicrystal was studied by in situ TEM during 1.5 MeV Xe+ ion irradiation at room temperature using the HVEM-Tandem Facility at Argon National Laboratory and examined in detail by HREM using a JEM2010 microscope at the University of New Mexico after the irradiation.

Organocatalyzed C–C Ring Construction: The Carreira Synthesis of (+)-Crotogoudin

2017 ◽  
Author(s):  
Douglass F. Taber
Keyword(s):  
National Laboratory ◽  
Unsaturated Aldehyde ◽  
Materia Medica ◽  
University Of New Mexico ◽  
Effective Strategies ◽  
Ester Enolate ◽  
Robinson Annulation ◽  
The University ◽  
Peptide Catalyst

Kazuaki Kudo of the University of Tokyo developed (Org. Lett. 2013, 15, 4964) a peptide catalyst for the enantioselective construction of 3 by the addition of 2 to 1. Thorsten Bach of the Technische Universität München devised (Science 2013, 342, 840; J. Am. Chem. Soc. 2013, 135, 14948) a Lewis acid organocatalyst for the photo­cyclization of 4 to 5. Albert Moyano of the Universitat de Barcelona effected (Eur. J. Org. Chem. 2013, 3103) enantioselective conjugate addition of 7 to 6 to give the cyclopentane 8. Daniel Romo of Texas A&M optimized (Nature Chem. 2013, 5, 1049) the addition of 9 to 10 to give the β-lactone 11. Kamal Kumar and Herbert Waldmann of the Technische Universität Dortmund found (Angew. Chem. Int. Ed. 2013, 52, 9576) that the addition of 12 to 13 followed by Bayer–Villiger oxidation and deacylation delivered 14 in high ee. David W. Lupton of Monash University opened (Angew. Chem. Int. Ed. 2013, 52, 9149) the cyclopropane of 15 in situ, leading to an ester enolate that added to 16 to give 17. Jeffrey S. Johnson of the University of North Carolina used (Chem. Sci. 2013, 4, 2828) an organocatalyst to mediate the addition of the prochiral 18 to 19, leading to 20. M. Belén Cid of the Universidad Autónoma de Madrid added (J. Org. Chem. 2013, 78, 10737) the nitroalkane 22 to the unsaturated aldehyde 21, leading, after intramolecular Julia-Kocienski addition, to the cyclohexene 23. Additions that pro­ceed in high ee with cyclopentenone and cyclohexenone are often not as selective with cycloheptenone 24. Wei Wang of the University of New Mexico and Wenhu Duan of the Shanghai Institute of Materia Medica observed (Tetrahedron Lett. 2013, 54, 3791) that addition of nitromethane and of nitroethane to 24 were both highly effective. Strategies have been developed for applying organocatalysis to the assembly of polycarbacyclic ring systems. Sanzhong Luo of the Beijing National Laboratory for Molecule Sciences uncovered (Synthesis 2013, 45, 1939) a simple amine that effi­ciently catalyzed the Robinson annulation of 26 with 27 to give 28.

Preparation of Benzene Derivatives: The Yu/Baran Synthesis of (+)-Hongoquercin A

2017 ◽  
Author(s):  
Douglass F. Taber
Keyword(s):  
Electrophilic Aromatic Substitution ◽  
University Of Michigan ◽  
Aromatic Substitution ◽  
Blocking Group ◽  
University Of Texas ◽  
University Of Houston ◽  
National University ◽  
Reformatsky Reagent ◽  
The University

Lutz Ackermann of the Georg-August-Universität Göttingen oxidized (Org. Lett. 2013, 15, 3484) the anisole derivative 1 to the phenol 2. Melanie S. Sanford of the University of Michigan devised (Org. Lett. 2013, 15, 5428) complementary condi­tions for either para acetoxylation of 3, illustrated, to give 4, or meta acetoxylation. Lukas J. Goossen of the Technische Universität Kaiserlautern developed (Synthesis 2013, 45, 2387) conditions for the cascade alkoxylation/decarboxylation of 5 to give 6. Cheol-Hong Cheon of Korea University showed (J. Org. Chem. 2013, 78, 12154) that the boronic acid of 7 could act as a blocking group during electrophilic aromatic substitution or, as illustrated, as an ortho directing group. It could then be removed by protodeboronation, leading to 8. Jun Wu of Zhejiang University coupled (Synlett 2013, 24, 1448) the phenol 9 with the bromo amide 10 to give an ether that, on exposure to KOH at elevated temperature, rearranged to the intermediate amide, that was then hydrolyzed to 11. Dong-Shoo Shin of Changwon National University reported (Tetrahedron Lett. 2013, 54, 5151) a similar protocol (not illustrated) to prepare unsubsti­tuted anilines. Guangbin Dong of the University of Texas, Austin used (J. Am. Chem. Soc. 2013, 135, 18350) a variation on the Catellani reaction to add 13 to the ortho bromide 12 to give the meta amine 14. Kei Manabe of the University of Shizuoka found (Angew. Chem. Int. Ed. 2013, 52, 8611) that the crystalline N-for­myl saccharin 16 was a suitable CO donor for the carbonylation of the bromide 15 to the aldehyde 17. John F. Hartwig of the University of California, Berkeley described (J. Org. Chem. 2013, 78, 8250) the coupling of the zinc enolate of an ester (Reformatsky reagent), either preformed or generated in situ, with an aryl bromide 18 to give 19. Olafs Daugulis of the University of Houston developed (Org. Lett. 2013, 15, 5842) conditions for the directed ortho phenoxylation of 20 with 21 to give 22. Yao Fu of the University of Science and Technology of China effected (J. Am. Chem. Soc. 2013, 135, 10630) directed ortho cyanation of 23 with 24 to give 25.

Alkylated Stereogenic Centers: The Jia Synthesis of (−)-Goniomitine

2017 ◽  
Author(s):  
Douglass F. Taber
Keyword(s):  
Organic Chemistry ◽  
Bimetallic Catalyst ◽  
The Other ◽  
Wild Type Enzyme ◽  
Enantiomerically Pure ◽  
Unsaturated Lactone ◽  
University Of Oxford ◽  
Stereogenic Centers ◽  
The University

John W. Wong of Pfizer and Kurt Faber of the University of Graz used (Adv. Synth. Catal. 2014, 356, 1878) a wild-type enzyme to reduce the nitrile 1 to 2 in high ee. Takafumi Yamagami of Mitsubishi Tanabe Pharma described (Org. Process Res. Dev. 2014, 18, 437) the practical diastereoselective coupling of the racemic acid 3 with the inexpensive pantolactone 4 to give, via the ketene, the ester 5 in high de. Takeshi Ohkuma of Hokkaido University devised (Org. Lett. 2014, 16, 808) a Ru/Li catalyst for the enantioselective addition of in situ generated HCN to an N-acyl pyrrole 6 to give 7 in high ee. Yujiro Hayashi of Tohoku University found (Chem. Lett. 2014, 43, 556) that an aldehyde 8 could be condensed with formalin, leading in high ee to the masked aldehyde 9. Stephen P. Fletcher of the University of Oxford prepared (Org. Lett. 2014, 16, 3288) the lactone 12 in high ee by adding an alkyl zirconocene, prepared from the alkene 11, to the unsaturated lactone 10. In a remarkable display of catalyst control, Masakatsu Shibasaki of the Institute of Microbial Chemistry and Shigeki Matsunaga of the University of Tokyo opened (J. Am. Chem. Soc. 2014, 136, 9190) the racemic aziridine 13 with malonate 14 using a bimetallic catalyst. One enantiomer of the aziridine was converted specifically to the branched product 15 in high ee. The other enantiomer of the aziridine was converted to the regioisomeric opening product. Kimberly S. Peterson of the University of North Carolina at Greensboro used (J. Org. Chem. 2014, 79, 2303) an enantiomerically-pure organophosphate to selec­tively deprotect the bis ester 16, leading to 17. Chunling Fu of Zhejiang University and Shengming Ma of the Shanghai Institute of Organic Chemistry showed (Chem. Commun. 2014, 50, 4445) that an organocatalyst could mediate the brominative oxi­dation of 18 to 19. The ee of the product was easily improved via selective crystalliza­tion of the derived dinitrophenylhydrazone. James P. Morken of Boston College developed (Org. Lett. 2014, 16, 2096) condi­tions for the allylation of an allylic acetate such as 20 with 21, to deliver the coupled product 22 with high maintenance of ee.

Reactions of Alkenes: The RajanBabu Synthesis of Pseudopterosin G-J Aglycone Dimethyl Ether

2015 ◽  
Author(s):  
Douglass F. Taber
Keyword(s):  
Medical Center ◽  
Selective Reduction ◽  
Oxidative Cleavage ◽  
University Of Texas ◽  
Furman University ◽  
National University ◽  
Institute Of Technology ◽  
Seoul National University ◽  
The University ◽  
Medical University

Xiangge Zhou of Sichuan University showed (Tetrahedron Lett. 2011, 52, 318) that even the monosubstituted alkene 1 was smoothly converted to the methyl ether 2 by catalytic FeCl3. Brian C. Goess of Furman University protected (J. Org. Chem. 2011, 76, 4132) the more reactive alkene of 3 as the 9-BBN adduct, allowing selective reduction of the less reactive alkene to give, after reoxidation, the monoreduced 4. Nobukazu Taniguchi of the Fukushima Medical University added (Synlett 2011, 1308) Na p-toluenesulfinate oxidatively to 1 to give the sulfone 5. Krishnacharya G. Akamanchi of the Indian Institute of Chemical Technology, Mumbai oxidized (Synlett 2011, 81) 1 directly to the bromo ketone 6. Osmium is used catalytically both to effect dihydroxylation, to prepare 8, and to mediate oxidative cleavage, as in the conversion of 7 to the dialdehyde 9. Ken-ichi Fujita of AIST Tsukuba devised (Tetrahedron Lett. 2011, 52, 3137) magnetically retrievable osmium nanoparticles that can be reused repeatedly for the dihydroxylation. B. Moon Kim of Seoul National University established (Tetrahedron Lett. 2011, 52, 1363) an extraction scheme that allowed the catalytic Os to be reused repeatedly for the oxidative cleavage. Maurizio Taddei of the Università di Siena showed (Synlett 2011, 199) that aqueous formaldehyde could be used in place of Co/H2 (syngas) for the formylation of 1 to 10. Hirohisa Ohmiya and Masaya Sawamura of Hokkaido University prepared (Org. Lett. 2011, 13, 1086) carboxylic acids (not illustrated) from alkenes using CO2. Joseph M. Ready of the University of Texas Southwestern Medical Center selectively arylated (Angew. Chem. Int. Ed. 2011, 50, 2111) the homoallylic alcohol 11 to give 12. Many reactions of alkenes are initiated by hydroboration, then conversion of the resulting alkyl borane. Hiroyuki Kusama of the Tokyo Institute of Technology photolyzed (J. Am. Chem. Soc. 2011, 133, 3716) 14 with 13 to give the ketone 15. William G. Ogilvie of the University of Ottawa added (Synlett 2011, 1113) the 9-BBN adduct from 1 to 16 to give 17. Professors Ohmiya and Sawamura effected (Org. Lett. 2011, 13, 482) a similar conjugate addition, not illustrated, of 9-BBN adducts to α,β-unsaturated acyl imidazoles.

Enantioselective Synthesis of Lactones and Cyclic Ethers

2011 ◽  
Author(s):  
Douglass Taber
Keyword(s):  
Hydroxy Acid ◽  
Addition Product ◽  
Single Step ◽  
Indian Institute ◽  
Cyclic Ethers ◽  
University Of Texas ◽  
Complementary Approach ◽  
Stereogenic Centers ◽  
The University ◽  
Work Up

Developments in organocatalysis have turned toward the enantioselective construction of lactones. Shi-Wei Luo and Liu-Zhu Gong of the University of Science and Technology of China have found (J. Org. Chem. 2007, 71, 9905) that catalyzed addition of acetone to an α-hydroxy acid 1 proceeded with high ee. Esterification of the addition product followed by reduction and acid work-up delivered the lactone 4 with high dr and ee. In a complementary approach, Jean-Marc Vincent and Yannick Landais of the University Bourdeaux-1 showed (Chem. Commun. 2007, 4782) that catalyzed condensation of an aldehyde with an α-hydroxy acid 5 delivered the tetronic acid 8 in high ee. It may be that 8 could also be reduced with useful selectivity. Cong-Gui Zhao of the University of Texas, San Antonio has devised conditions (Organic Lett. 2007, 9, 2745) for the condensation of the keto phosphonates such as 10 with aldehydes to give, after oxidation, the δ-lactone 12. Carbohydrates such as glucose 13 are inexpensive, molecularly-complex starting materials. Subhash Chandra Taneja of the Indian Institute of Integrative Medicine, Jammu Tawi, has found conditions (J. Org. Chem. 2007, 72, 8965) for the single-step I2 -catalyzed transformation of 13 to 14, in which each of the alcohols have been differentiated. In a complementary approach described (Tetrahedron Lett. 2007, 48, 6389) by Tushar Kanti Chakraborty of the Indian Institute of Chemical Technology, Hyderabad, Ti-mediated reduction of 15 was shown to be highly diastereoselective, setting the two new stereogenic centers (marked by*) in 16. Building on work by Mead, Daniel Romo of Texas A&M has shown (J. Org. Chem. 2007, 72, 9053) that reductive cyclization of 18 also proceeded with high diastereocontrol, to give 19. As illustrated by the conversion of 20 to 21 reported (Tetrahedron Lett. 2007, 48, 7351) by Zsuzsa Juhász and László Somsák of the University of Debrecen, six-membered ring cyclic ethers can also be formed from carbohydrate precursors. Richard E. Taylor of the University of Notre Dame has taken advantage (Angew. Chem. Int. Ed. 2007, 46, 6874) of the “chemical chameleon” nature of a sulfone, using it both the stablilize the anion for intramolecular alkylation, to form 23, and as a leaving group, leading to 24.

Arrays of Stereogenic Centers: The Carbery Synthesis of Mycestericin G

2015 ◽  
Author(s):  
Douglass F. Taber
Keyword(s):  
Dipolar Cycloaddition ◽  
General Strategy ◽  
Stanford University ◽  
Keto Ester ◽  
Stereogenic Centers ◽  
Crystalline Adduct ◽  
Enantioselective Addition ◽  
The University ◽  
Pais Vasco

Chi-Ming Che of the University of Hong Kong devised (Chem. Commun. 2011, 47, 11204) a manganese catalyst for the enantioselective cis-dihydroxylation of electron-deficient alkenes such as 1. Christine Greck of Université de Versailles-St-Quentin effected (Tetrahedron Lett. 2012, 53, 1085) enantioselective alkoxylation of 3, remarkably without β-elimination. Keiji Maruoka of Kyoto University developed (J. Am. Chem. Soc. 2012, 134, 7516) an organocatalyst for the enantioselective anti addition of 5 to 6 to give 7. Barry M. Trost of Stanford University developed (J. Am. Chem. Soc. 2012, 134, 2075) a Mg catalyst for the enantioselective addition of ethyl diazoacetate to an aldehyde 8, and carried the adduct onto 9. Professor Maruoka designed (Angew. Chem. Int. Ed. 2012, 51, 1187) for the enantioselective addition of a ketone 10 to the alkynyl ketone 11 to give 12. Naoya Kumagai and Masakatsu Shibasaki of the Institute of Microbial Chemistry found (Org. Lett. 2012, 14, 3108) that 14 could be added under very soft conditions to 13 to give the anti adduct 15. René Peters of the Universität Stuttgart added (Adv. Synth. Catal. 2012, 354, 1443) the azlactone formed in situ to 17 in a conjugate sense to give 18. Kaïss Aouadi and Jean-Pierre Praly of the Université de Lyon prepared (Tetrahedron Lett. 2012, 53, 2817) the nitrone 19 from the inexpensive (–)-menthone. Dipolar cycloaddition to a range of alkenes proceeded with substantial diastereocontrol, as illustrated for 20, which gave the crystalline adduct 21. Jeffrey S. Johnson of the University of North Carolina reduced (J. Am. Chem. Soc. 2012, 134, 7329) the α-keto ester 22 under equilibrating conditions to give the lactone 23. Claudio Palomo of the Universidad del País Vasco alkylated (J. Org. Chem. 2012, 77, 747) the aldehyde 24 with 25 to give the diester 26. Damien Bonne and Jean Rodriguez of Aix-Marseille Université added (Adv. Synth. Catal. 2012, 354, 563) the α-keto ester 27 to 28 in a conjugate sense to give 29. Glenn C. Micalizio of Scripps/Florida developed (Angew. Chem. Int. Ed. 2012, 51, 5152) a general strategy for the stereocontrolled construction of skipped-conjugate dienes such as 30.

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