3761-94-2Relevant academic research and scientific papers
Photoinduced Fragmentation Borylation of Cyclic Alcohols and Hemiacetals
Aggarwal, Varinder K.,Madhavachary, Rudrakshula,Noble, Adam,Shu, Chao
supporting information, p. 7213 - 7218 (2020/10/12)
A visible-light photoinduced fragmentation borylation of O-phthalimido cycloalkanols with bis(catecholato)diboron is described. Structurally diverse keto and formyloxy alkyl boronic esters are shown to be conveniently prepared by radical-mediated ring opening of cyclic alcohols and hemiacetals, respectively. The reactions proceed under mild conditions in the absence of additives or photocatalysts, display excellent functional group tolerance, and are shown to allow cleavage of 4-, 5-, 6-, and 7-membered ring substrates. The mechanism proceeds via sequential homolytic N-O and C-C bond cleavages, the latter of which involves β-scission of an alkoxy radical, generating a carbonyl and an alkyl radical that is trapped by the diboron reagent. Spectroscopic studies suggest direct photoexcitation of either the phthalimide or diboron substrates with blue light can initiate a radical chain mechanism.
Efficient C-H Amination Catalysis Using Nickel-Dipyrrin Complexes
Betley, Theodore A.,Clarke, Ryan M.,Dong, Yuyang,Porter, Gerard J.
supporting information, p. 10996 - 11005 (2020/07/08)
A dipyrrin-supported nickel catalyst (AdFL)Ni(py) (AdFL: 1,9-di(1-adamantyl)-5-perfluorophenyldipyrrin; py: pyridine) displays productive intramolecular C-H bond amination to afford N-heterocyclic products using aliphatic azide substrates. The catalytic amination conditions are mild, requiring 0.1-2 mol% catalyst loading and operational at room temperature. The scope of C-H bond substrates was explored and benzylic, tertiary, secondary, and primary C-H bonds are successfully aminated. The amination chemoselectivity was examined using substrates featuring multiple activatable C-H bonds. Uniformly, the catalyst showcases high chemoselectivity favoring C-H bonds with lower bond dissociation energy as well as a wide range of functional group tolerance (e.g., ethers, halides, thioetheres, esters, etc.). Sequential cyclization of substrates with ester groups could be achieved, providing facile preparation of an indolizidine framework commonly found in a variety of alkaloids. The amination cyclization reaction mechanism was examined employing nuclear magnetic resonance (NMR) spectroscopy to determine the reaction kinetic profile. A large, primary intermolecular kinetic isotope effect (KIE = 31.9 ± 1.0) suggests H-atom abstraction (HAA) is the rate-determining step, indicative of H-atom tunneling being operative. The reaction rate has first order dependence in the catalyst and zeroth order in substrate, consistent with the resting state of the catalyst as the corresponding nickel iminyl radical. The presence of the nickel iminyl was determined by multinuclear NMR spectroscopy observed during catalysis. The activation parameters (ΔH? = 13.4 ± 0.5 kcal/mol; ΔS?= -24.3 ± 1.7 cal/mol·K) were measured using Eyring analysis, implying a highly ordered transition state during the HAA step. The proposed mechanism of rapid iminyl formation, rate-determining HAA, and subsequent radical recombination was corroborated by intramolecular isotope labeling experiments and theoretical calculations.
Azetidine derivatives and synthesis method thereof
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Paragraph 0063-0065, (2019/03/26)
The invention belongs to the field of chemical synthesis, and discloses an azetidine derivative and a synthesis method thereof. The structural formula of the target product azetidine derivatives is asshown in formulae (I), (II), (III), (IV) and (V). The compounds of the formulae are compounds containing an azetidine skeleton, and a nitrogen atom in the skeleton is protected by 2-picolinic acid. The target product azetidine derivatives can be: azetidinyl amide derivatives, azabicyclo[x.1.1] amide derivatives (x=3, 4, 5, 6, 7, 8, 9), azabicyclo[4.1.1] amide derivatives having a substituent at the ring, azabicyclo[4.2.0] amide derivatives and azetidine derivatives containing spirocyclic quaternary carbon. The azetidine derivatives of the present invention have certain protective effect on hydrogen peroxide-induced oxidative stress damage of HC cells.
Controllable Intramolecular Unactivated C(sp3)-H Amination and Oxygenation of Carbamates
Guo, Qihang,Ren, Xiang,Lu, Zhan
supporting information, p. 880 - 884 (2019/05/16)
Dual catalyst-controlled intramolecular unactivated C(sp3)-H amination and oxygenation of carbamates merging visible-light photocatalysis and earth-abundant transition metal catalysis have been reported. Useful amino alcohol and diol derivatives could be selectively obtained from readily available tertiary alcohol derivatives. The possible mechanisms have been proposed via a 1,5-HAT process followed by Lewis acid-controlled cyclization. The nickel and zinc catalysts inhibit the formation of oxygenation and amination products, respectively. An interesting phenomenon of chirality transfer is also observed.
Polycyclic Azetidines and Pyrrolidines via Palladium-Catalyzed Intramolecular Amination of Unactivated C(sp3)-H Bonds
Zhao, Jie,Zhao, Xiao-Jing,Cao, Pei,Liu, Ji-Kai,Wu, Bin
supporting information, p. 4880 - 4883 (2017/09/23)
A novel strategy to construct complex polycyclic nitrogen-containing heterocycles from aliphatic amines via picolinamide-assisted palladium-catalyzed C-H bond activation reaction was reported. The reaction exhibits broad substrate scope for the synthesis of various azabicyclic scaffolds, including azetidines and tropane-class alkaloids. Application of this method to naturally occurring (-)-cis-myrtanylamine, an unprecedented type of carbon-carbon bond activation, in which the electron-pair involved initiates an intramolecular "SN2-like" displacement of a cyclopalladium-fragment from a tertiary center, is described.
Synthesis and cannabinoid receptor activity of ketoalkenes from Echinacea pallida and nonnatural analogues
Egger, Michael,Pellett, Patrina,Nickl, Kathrin,Geiger, Sarah,Graetz, Stephanie,Seifert, Roland,Heilmann, Joerg,Koenig, Burkhard
scheme or table, p. 10978 - 10984 (2009/10/02)
Despite its popularity and widespread use, the efficacy of Echinacea products remains unclear and controversial. Among the various compounds isolated from Echinacea, ketoalkenes and ketoalkenynes exclusively found in the pale purple coneflower (E. pallida) are major components of the extracts. In contrast to E. purpurea alkamides, these compounds have not been synthesized and studied for immunostimulatory effects. We present a practical and useful synthetic approach to the ketoalkenes using palladium-catalyzed cross-coupling reactions and the pharmaceutical results at the human cannabinoid receptors. The synthetic route developed provides overall good yields for the ketoalkenes and is applicable to other natural products with similar 1,4-diene motifs. No significant activity was observed at either receptor, indicating that the ketoalkenes from E. pallida are not responsible for immunomodulatory effects mediated via the cannabinergic system. However, newly synthesized non-natural analogues showed micro-molar potency at both cannabinoid receptors.
Silica Gel-supported Zinc Borohydride. Part 3. Regioselective Reductive Cleavage of Methylenecycloalkane Oxides to the Less-substituted Alcohols
Ranu, Brindaban C.,Das, Asish R.
, p. 1881 - 1882 (2007/10/02)
Highly selective reductive cleavage of methylenecycloalkane oxides to less-substituted alcohols has been achieved by a simple procedure using silica gel supported zinc borohydride in tetrahydrofuran.
Cycloalkyl esters of mercaptoalkanoic acids
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, (2008/06/13)
Described are the cycloalkyl esters of mercaptoalkanoic acids defined according to the structure: STR1 wherein R1 represents hydrogen or methyl; R2 represents mono C1 -C4 alkyl substituted or unsubstituted C5 -C8 cycloalkyl; R3 represents hydrogen or methyl; and N represents 0, 1 or 2 and uses thereof in augmenting or enhancing the aroma or taste of foodstuffs.
LIGHT-MEDIATED TRANSFORMATIONS OF OLEFINS INTO ALCOHOLS: REACTIONS OF HYDROXYL RADICALS WITH CYCLOALKENES
Sonawane, H. R.,Nanjundiah, B. S.,Kelkar, R. G.
, p. 6673 - 6682 (2007/10/02)
Reactions of hydroxyl radicals, generated by photodecomposition of hydrogen peroxide in acetonitrile, with a wide variety of cycloalkenes have been examined.The results show that the major reaction is the addition of hydroxyl radicals to the less substituted end of the double bond, furnishing the secondary alcohols.The reactivity pattern and the observed regio- and stereoselectivity clearly reveal that the steric parameters associated with the substrates play a dominant role in directing the addition reactions.More importantly, this study led to the development of a new methodology for the facile conversions of olefins essentially into secondary alcohols, and includes a few examples which demonstrate the potential of the method.
Photo-induced Reactions of Some Epoxides in Isopropanol: Effect of Structural Parameters on Photoreduction and Photosolvolysis
Sonawane, H. R.,Sethi, S. C.,Merchant, S. N.
, p. 934 - 939 (2007/10/02)
Competing photoreduction and photosolvolysis reactions have been observed in the photolysis of a number of epoxides (1-8).Certain epoxides display extreme photobehaviour; photosolvolysis is the exclusive process in 5 and 7 whereas 8 undergoes only photoreduction.A novel photo-Wagner-Meerwein rearrangement occurs in the photosolvolysis of benzonorbornene epoxide (7).Mechanisms involving radical and ionic intermediates are discussed.
