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.

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.

Crystallization of nano-size thallous oxide during ion irradiation of Tl-Ba-Ca-Cu-O high-temperature superconductors

1995 ◽  
Vol 53 ◽  
pp. 214-215
Author(s):  
P. P. Newcomer ◽  
L. M. Wang ◽  
M. L. Miller ◽  
R. C. Ewing
Keyword(s):  
High Temperature ◽  
Ion Irradiation ◽  
Ion Beam ◽  
High Temperature Superconductors ◽  
National Laboratory ◽  
Argonne National Laboratory ◽  
Planetary Science ◽  
University Of New Mexico ◽  
The University ◽  
Nano Size

The Tl-Ba-Ca-Cu-O class of type-II high temperature superconductors (HTS) have Tc's as high as 125K. Although they have good critical current values, when a field is applied the weak pinning and consequent flow of magnetic vortices are a major impediment to the usefulness of these materials. Ion irradiation has been shown to enhance the pinning. High quality single crystals, as determined with x-ray precession and HRTEM, with sharp HTS Meissner signals, were irradiated with 1.5 MeV Kr+ and Xe+ ions using the HVEM-Tandem facility at Argonne National Laboratory. Ion beam microstructural modification was studied in-situ using electron diffraction and after irradiation using HRTEM and nano-beam EDS on Tl-1212 and Tl-2212 (numbers designate the stoichiometry Tl-Ba- Ca-Cu-O) single-crystal HTS. After irradiation, microstructure was studied using the JEOL 2010 in the Earth and Planetary Science Department at the University of New Mexico in order to characterize the resulting irradiation-induced nano-size precipitates.

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.

Integrated Chemical Effects Head Loss Experiments Using Multiconstituent Fibrous Debris Beds

2016 ◽  
Vol 3 (1) ◽  
Author(s):  
Daniel LaBrier ◽  
Amir Ali ◽  
Kerry J. Howe ◽  
Edward D. Blandford
Keyword(s):  
Cooling System ◽  
Product Formation ◽  
Head Loss ◽  
University Of New Mexico ◽  
Chemical Effects ◽  
Loss Of Coolant Accident ◽  
Chemical Conditions ◽  
Core Cooling ◽  
The University

The chemical head loss experiment (CHLE) program has been designed to acquire realistic material release and product formation in containment under post-loss of coolant accident (LOCA) conditions and their impact on the measured head loss through the use of modified debris beds developed at the University of New Mexico (UNM). A full-scale water chemistry test was conducted under Vogtle containment chemistry conditions to determine the release of these materials and the resulting head loss response of the formed products within the emergency core cooling system (ECCS) under prototypical chemical conditions. The test was designed to investigate material corrosion with the presence of excess aluminum and a nonprototypical temperature profile (80 °C for 120 h) to promote the production of aluminum precipitates. The head loss measured within the first 72 h of the test either surpassed the operational limits of the equipment or caused a failure within the system. The increase in head loss is not attributed to the formation of in situ precipitates but to a physical reaction of the epoxy used in constructing the debris beds to the local chemistry during the early stages of the test.

Asymmetric C–C Bond Formation

2015 ◽  
Author(s):  
Tristan H. Lambert
Keyword(s):  
Michael Addition ◽  
Enantiomeric Excess ◽  
Unsaturated Aldehyde ◽  
Phosphorus Ligands ◽  
University Of New Mexico ◽  
Amine Catalysis ◽  
Internal Olefin ◽  
The Stability ◽  
The University ◽  
Stereogenic Center

Andrew G. Myers at Harvard reported (Angew. Chem. Int. Ed. 2012, 51, 4568) the alkylation of the pseudophenamine amide 1 selectively setting the quaternary stereogenic center of 2. This is an effective replacement for his previously reported pseudoephedrine, now a controlled substance. Amine catalysis has enabled numerous methods for the asymmetric α-functionalization of aldehydes, although α-alkylation remains a significant challenge. David W.C. MacMillan at Princeton developed (J. Am. Chem. Soc. 2012, 134, 9090) an α-vinylation of aldehydes 3 with vinyliodoniums 5, which relied on the “synergistic combination” of the amine catalyst 4 and copper(I) bromide. The stability of the β,γ-unsaturated aldehyde products under the reaction conditions is notable. A procedure for the asymmetric β-vinylation of α,β-unsaturated aldehydes such as 7 was developed (Eur. J. Org. Chem. 2012, 2774) by Claudio Palomo at the Universidad del Pais Vasco in Spain. Amine 8 catalyzed the enantioselective Michael addition of β-nitroethyl sulfone 9 to 7 followed by acetalization and elimination of HNO2 and SO2Ph furnished products such as 10 in high enantiomeric excess. In a conceptually related reaction, a surrogate for acetate as a nucleophile was reported (Chem. Commun. 2012, 48, 148) by Wei Wang at the University of New Mexico and Jian Li of the East China University of Science and Technology. In this case, amine 13-catalyzed Michael addition of pyridyl sulfone 11 to unsaturated aldehyde 12, followed by acetalization and reductive removal of the sulfone, gave rise to the ester product 14 with very high ee. Asymmetric hydroformylation offers a powerful approach for the synthesis of carbon stereocenters, but controlling the regioselectivity of the reaction remains a challenge with many substrate classes. Christopher J. Cobley of Chirotech Technology Ltd. (UK) and Matthew L. Clarke at the University of St. Andrews showed (Angew. Chem. Int. Ed. 2012, 51, 2477) that the mixed phosphine-phosphite ligand “bobphos” 16 (bobphos = best of both phosphorus ligands) provided significant selectivities for the branched hydroformylation products, up to 10:1 b:l in the case of 15. Another major challenge for hydroformylation is to control the regioselectivity of internal olefin substrates.

Electron and ion irradiation-induced dissolution of mechanical twins in the intermetalic U3Si: An in situ HVEM study

1989 ◽  
Vol 47 ◽  
pp. 652-653
Author(s):  
Charles W. Allen ◽  
Robert C. Birtcher
Keyword(s):  
Elevated Temperatures ◽  
Ion Irradiation ◽  
Ion Beam ◽  
National Laboratory ◽  
Argonne National Laboratory ◽  
Heavy Ion ◽  
High Energy ◽  
Mechanical Twinning ◽  
In Situ Experiments

The uranium silicides, including U3Si, are under study as candidate low enrichment nuclear fuels. Ion beam simulations of the in-reactor behavior of such materials are performed because a similar damage structure can be produced in hours by energetic heavy ions which requires years in actual reactor tests. This contribution treats one aspect of the microstructural behavior of U3Si under high energy electron irradiation and low dose energetic heavy ion irradiation and is based on in situ experiments, performed at the HVEM-Tandem User Facility at Argonne National Laboratory. This Facility interfaces a 2 MV Tandem ion accelerator and a 0.6 MV ion implanter to a 1.2 MeV AEI high voltage electron microscope, which allows a wide variety of in situ ion beam experiments to be performed with simultaneous irradiation and electron microscopy or diffraction.At elevated temperatures, U3Si exhibits the ordered AuCu3 structure. On cooling below 1058 K, the intermetallic transforms, evidently martensitically, to a body-centered tetragonal structure (alternatively, the structure may be described as face-centered tetragonal, which would be fcc except for a 1 pet tetragonal distortion). Mechanical twinning accompanies the transformation; however, diferences between electron diffraction patterns from twinned and non-twinned martensite plates could not be distinguished.

Environmental cell studies of deformation and fracture

1990 ◽  
Vol 48 (4) ◽  
pp. 516-517
Author(s):  
H. K. Birnbaum ◽  
I. M. Robertson
Keyword(s):  
National Laboratory ◽  
Argonne National Laboratory ◽  
Damage Threshold ◽  
Chromatic Aberration ◽  
Good Choice ◽  
Point Of View ◽  
Deformation And Fracture ◽  
Environmental Cell ◽  
Gas Molecules ◽  
The University

Studies of the effects of hydrogen environments on the deformation and fracture of fcc, bcc and hep metals and alloys have been carried out in a TEM environmental cell. The initial experiments were performed in the environmental cell of the HVEM facility at Argonne National Laboratory. More recently, a dedicated environmental cell facility has been constructed at the University of Illinois using a JEOL 4000EX and has been used for these studies. In the present paper we will describe the general design features of the JEOL environmental cell and some of the observations we have made on hydrogen effects on deformation and fracture.The JEOL environmental cell is designed to operate at 400 keV and below; in part because of the available accelerating voltage of the microscope and in part because the damage threshold of most materials is below 400 keV. The gas pressure at which chromatic aberration due to electron scattering from the gas molecules becomes excessive does not increase rapidly with with accelerating voltage making 400 keV a good choice from that point of view as well. A series of apertures were placed above and below the cell to control the pressures in various parts of the column.

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