Results 41 to 50 of about 3,707,282 (391)

Metal-Free Synthesis of N-Heterocycles via Intramolecular Electrochemical C-H Aminations

Frontiers in Chemistry, 2022
N-heterocycles are key structural units in many drugs, biologically interesting molecules and functional materials. To avoid the residues of metal catalysts, the construction of N-heterocycles under metal-free conditions has attracted much research ...
Huiqiao Wang, Yongjun Zheng, Hucheng Xu, Jiaru Zou, Congrui Jin   +4 more
doaj   +1 more source

The iso-Nazarov reaction [PDF]

, 2017
The construction of five-membered rings is essential in organic chemistry. In this context, pentannulation reactions that provide a straightforward access to cyclopentenones are of particular interest, as these structures are not only embedded in ...
Marsili, Lucía A., Mischne, Mirta Paulina, Riveira, Martín Jorge   +2 more
core   +1 more source

Exact theory of kinkable elastic polymers [PDF]

, 2004
The importance of nonlinearities in material constitutive relations has long been appreciated in the continuum mechanics of macroscopic rods. Although the moment (torque) response to bending is almost universally linear for small deflection angles, many ...
A. Y. Grosberg, C. A. Sucato, D. Shore, E. N. Trifonov, G. B. Arfken, H. Yamakawa, J. Bernet, J. J. Sakurai, L. D. Landau, O. Kratky, P. C. Nelson, Paul A. Wiggins, Philip C. Nelson, R. P. Feynman, Rob Phillips   +14 more
core   +5 more sources

Engineering of Cyclodextrin Product Specificity and pH Optima of the Thermostable Cyclodextrin Glycosyltransferase from Thermoanaerobacterium thermosulfurigenes EM1 [PDF]

, 1998
The product specificity and pH optimum of the thermostable cyclodextrin glycosyltransferase (CGTase) from Thermoanaerobacterium thermosulfurigenes EM1 was engineered using a combination of x-ray crystallography and site-directed mutagenesis.
Bauke W. Dijkstra, Bhat, Bradford, Brünger, Davies, Engh, Fujiwara, Haeckel, Harata, Jones, Joost C.M. Uitdehaag, Kabsch, Klein, Klein, Kleywegt, Knegtel, Knegtel, Koshland, Lamzin, Laskowski, Lawson, Lazzaroni, Lubbert Dijkhuizen, Monma, Nakamura, Nakamura, Norman, Pedersen, Penninga, Qian, Read, Reinetta M. Buitelaar, Richèle D. Wind, Sambrook, Sanger, Schmid, Starnes, Strokopytov, Strokopytov, Svensson, Takase, Takusagawa, Tronrud, Wind, Yanisch-Perron   +44 more
core   +2 more sources

The effect of host structure on the selectivity and mechanism of supramolecular catalysis of Prins cyclizations. [PDF]

, 2015
The effect of host structure on the selectivity and mechanism of intramolecular Prins reactions is evaluated using K12Ga4L6 tetrahedral catalysts. The host structure was varied by modifying the structure of the chelating moieties and the size of the ...
Bergman, Robert G, Burford, Kristen N, Hart-Cooper, William M, Ozores, Haxel Lionel, Raymond, Kenneth N, Toste, F Dean, Triano, Rebecca M, Yaghoubi, Parastou, Zhao, Chen   +8 more
core   +2 more sources

Synthesis of 4-amino-5-fluoropyrimidines and 5-amino-4-fluoropyrazoles from a β-fluoroenolate salt

Beilstein Journal of Organic Chemistry, 2020
A synthesis of fluorinated pyrimidines under mild conditions from amidine hydrochlorides and the recently described potassium 2-cyano-2-fluoroethenolate was developed. A broad substrate scope was tested and mostly excellent yields were obtained.
Tobias Lucas, Jule-Philipp Dietz, Till Opatz   +2 more
doaj   +1 more source

Synthesis and investigation of solvent effects on the ultraviolet absorption spectra of 5-substituted-4-methyl-3-cyano-6-hydroxy-2-pyridones [PDF]

Journal of the Serbian Chemical Society, 2001
A number of 5-substituted-4-methyl-3-cyano-6-hydroxy-2-pyridones from cyanoacetamide and the corresponding alkyl ethyl acetoacetates were synthesized according to modified literature procedures. The alkyl ethyl acetoacetates were obtained by the
Mijin Dušan Ž., Ušćumlić Gordana S., Valentić Nataša V.   +2 more
doaj   +1 more source

The unpredictably eruptive dynamics of spruce budworm populations in eastern Canada

Population Ecology, EarlyView.
We examine historical population data for spruce budworm from several locations through the period 1930–1997, and use density‐dependent recruitment curves to test whether the pattern of population growth over time is more consistent with Royama's (1984; Ecological Monographs 54:429–462) linear R(t) model of harmonic oscillation at Green River New ...
Barry J. Cooke, Jacques Régnière
wiley   +1 more source

Network topology drives population temporal variability in experimental habitat networks

Population Ecology, EarlyView.
Habitat patches connected by dispersal pathways form habitat networks. We explored how network topology affects population outcomes in laboratory experiments using a model species (Daphnia carinata). Central habitat nodes in complex lattice networks exhibited lower temporal variability in population sizes, suggesting they support more stable ...
Yiwen Xu, J. Angus Webb, William D. Bovill, Elise L. King   +3 more
wiley   +1 more source

An Efficient Synthesis of Novel 4-Aryl-2-thioxo-3,4-dihydro-1H-pyrimido[1,2-a][1,3,5]triazin-6(2H)-ones and Their Antibacterial Activity

Molbank, 2022
New substituted 4-aryl-8-methyl-2-thioxo-1,2,3,4-tetrahydro-6H-pyrimido[1,2-a][1,3,5]triazin-6-one 8a–b and ethyl 4-aryl-6-oxo-2-thioxo-1,3,4,6-tetrahydro-2H-pyrimido[1,2-a][1,3,5]triazine-7-carboxylate 8c–e were synthesized by the reaction of the ...
Do Van Quy, Nguyen Van Hung, Nadezhda Stolpovskaya, Aleksey Kruzhilin, Svetlana S. Olshannikova, Marina Holyavka, Vladimir Sulimov, Khidmet Shikhaliev   +7 more
doaj   +1 more source