- A bioorthogonal ligation of cyclopropenones mediated by triarylphosphines
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Bioorthogonal chemistries have been widely used to probe biopolymers in living systems. To date, though, only a handful of broadly useful transformations have been identified because of the stringent requirements placed on the reactants. Here we report a novel bioorthogonal ligation between cyclopropenones and functionalized phosphines. These components are stable in physiological buffers and react rapidly with one another to form covalent adducts. The cyclopropenone ligation is also distinct from other bioorthogonal chemistries in that it makes use of readily accessible, commercially available reagents and proceeds via a nucleophilic reaction pathway. On the basis of these features, the cyclopropenone ligation is poised to join the ranks of chemistries with utility in living systems.
- Shih, Hui-Wen,Prescher, Jennifer A.
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- Novel Ag(I)-catalysis of an intramolecular 1,3-dipolar cycloaddition
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Acetylenic α-diazoketones, bearing gem-dimethyl substituents in the α' position, were found to undergo an intramolecular 1,3-dipolar cycloaddition reaction in the presence of silver (I) as catalyst. In that instance, bicyclic pyrazole derivatives were isolated in 47 to 55% yield, even in the conditions of the Arndt-Eistert reaction. The requirement for gem-dimethyl substitution in acyclic substrates is rationalized in terms of steric effects on conformational energies in the transition state.
- Kende, Andrew S.,Journet, Michel
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- INDAZOLES AS LRRK2 INHIBITORS
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The present invention is directed to indazole compounds which are inhibitors of LRRK2 and are useful in the treatment of CNS disorders.
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Page/Page column 135
(2020/10/09)
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- Rhodium-Catalyzed Regio- and Enantioselective Addition of N-Hydroxyphthalimide to Allenes: A Strategy to Synthesize Chiral Allylic Alcohols
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We achieved the first Rh-catalyzed regio- and enantioselective additions of N-hydroxyphthalimide to allenes. This transformation is accomplished via mild reaction conditions, leveraging on Josiphos SL-J003-2 as a chiral ligand to furnish branched O-allyl compounds in good yields with moderate to excellent enantioselectivities. The substrate scope is broad, and various functional groups are tolerated. The utility of this methodology is elaborated by transformation to allylic alcohols with different functional groups as well as to chiral O-allyl hydroxylamines.
- Liu, Zi,Breit, Bernhard
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supporting information
p. 300 - 303
(2018/01/17)
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- Catalyst-Free Synthesis of Borylated Lactones from Esters via Electrophilic Oxyboration
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A catalyst-free oxyboration reaction of alkynes is developed. The resulting borylated isocoumarins and 2-pyrones are isolated as boronic acids, pinacolboronate esters, or potassium organotrifluoroborate salts, providing a variety of bench-stable organobor
- Faizi, Darius J.,Issaian, Adena,Davis, Ashlee J.,Blum, Suzanne A.
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supporting information
p. 2126 - 2129
(2016/03/05)
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- Catalyst-Free Formal Thioboration to Synthesize Borylated Benzothiophenes and Dihydrothiophenes
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The first ring-forming thioboration reaction of C?C π bonds is reported. This catalyst-free method proceeds in the presence of a commercially available external electrophilic boron source (B-chlorocatecholborane) in good to high yields. The method is scalable and tolerates a variety of functional groups that are intolerant of other major borylation methods. The resulting borylated benzothiophenes participate in a variety of in situ derivatization reactions, showcasing that these borylated intermediates do not need to be isolated prior to downstream functionalization. This methodology has been extended to the synthesis of borylated dihydrothiophenes. Mechanistic experiments suggest that the operative mechanistic pathway is through boron-induced activation of the alkyne followed by electrophilic cyclization, as opposed to S?B σ bond formation, providing a mechanistically distinct pathway to the thioboration of C?C π bonds.
- Faizi, Darius J.,Davis, Ashlee J.,Meany, Fiach B.,Blum, Suzanne A.
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supporting information
p. 14286 - 14290
(2016/11/11)
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- Alkoxyboration: Ring-closing addition of B-O σ bonds across alkynes
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For nearly 70 years, the addition of boron-X σ bonds to carbon-carbon multiple bonds has been employed in the preparation of organoboron reagents. However, the significantly higher strength of boron-oxygen bonds has thus far precluded their activation for addition, preventing a direct route to access a potentially valuable class of oxygen-containing organoboron reagents for divergent synthesis. We herein report the realization of an alkoxyboration reaction, the addition of boron-oxygen σ bonds to alkynes. Functionalized O-heterocyclic boronic acid derivatives are produced using this transformation, which is mild and exhibits broad functional group compatibility. Our results demonstrate activation of this boron-O σ bond using a gold catalysis strategy that is fundamentally different from that used previously for other boron addition reactions.
- Hirner, Joshua J.,Faizi, Darius J.,Blum, Suzanne A.
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supporting information
p. 4740 - 4745
(2014/04/17)
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- Alkyne-mediated domino hydroformylation/double cyclization: Mechanistic insight and synthesis of (±)-tashiromine
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A novel domino reaction, alkyne-mediated domino hydroformylation/double cyclization, has been developed for rapid preparation of indolizidine type alkaloids. DFT calculations were applied for rationales of reactivity and selectivity. A concise synthesis of tashiromine as the application of the methodology is also reported.
- Chiou, Wen-Hua,Lin, Yi-Huei,Chen, Guei-Tang,Gao, Yu-Kai,Tseng, Yu-Che,Kao, Chien-Lun,Tsai, Jui-Chi
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supporting information; experimental part
p. 3562 - 3564
(2011/04/26)
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- Copper-catalyzed 1,2-double amination of 1-halo-1-alkynes. Concise synthesis of protected tetrahydropyrazines and related heterocyclic compounds
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Reaction of N,N′-di(p-toluenesulfonyl)-1,2-diamine, 1-bromo-1-alkyne, K3PO4, and a catalytic amount of CuI in hot DMF afforded N,N′-di(p-toluenesulfonyl)-1,2,3,4-tetrahydropyrazines in good yields. The reaction most likely involves (i) monoalkynylation of the diamine derivative with 1-bromo-1-alkyne, and (ii) 6-endo-dig ring closure between the acetylenic bond and another sulfonylamine moiety of the diamine. When the starting 1,2-diamine derivative was replaced with N,N′-di(p-toluenesulfonyl)-1,3-diamine or N-(p-toluenesulfonyl)-2-amino-1-ethanol, the corresponding seven-membered diazacycle or six-membered N,O-heterocycle was produced. In addition, 1,1-dibromo-1-alkene could be used in place of 1-bromo-1-alkyne. Copyright
- Fukudome, Yasuhiro,Naito, Hiroyuki,Hata, Takeshi,Urabe, Hirokazu
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p. 1820 - 1821
(2008/09/18)
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- Reaction of dicarbonates with carboxylic acids catalyzed by weak Lewis acids: General method for the synthesis of anhydrides and esters
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The reaction between carboxylic acids (RCOOH) and dialkyl dicarbonates [(R1OCO)2O], in the presence of a weak Lewis acid such as magnesium chloride and the corresponding alcohol (R1OH) as the solvent, leads to the esters RCOOR1 in excellent yields. The mechanism involves a double addition of the acid to the dicarbonate, affording a carboxylic anhydride [(RCO)2O], R1OH and carbon dioxide. The esters arise from the attack of the alcohols on the anhydrides. Exploiting the lesser reactivity of tert-butyl alcohol in comparison with other alcohols, a clean synthesis of both carboxylic anhydrides and esters has been set up. In the former reaction, an acid/Boc2O molecular ratio of 2:1 leads to the anhydride in good to excellent yields, depending on the stability of the resulting anhydride to the usual workup conditions. In the latter reaction, stoichiometric mixtures of the acid and Boc2O are allowed to react with a twofold excess of a primary alcohol, secondary alcohol or phenol (R 2OH) to give the corresponding esters (RCOOR2). Purification of the products is particularly easy since all byproducts are volatile or water soluble. A very easy chromatography is required only in the case of nonvolatile alcohols. A broad variety of sensitive functional groups is tolerated on both the acid and the alcohol, in particular a high chemoselectivity is observed. In fact, no transesterification processes occur with the acid-sensitive acetoxy group and methyl esters. Georg Thieme Verlag Stuttgart.
- Bartoli, Giuseppe,Bosco, Marcella,Carlone, Armando,Dalpozzo, Renato,Marcantoni, Enrico,Melchiorre, Paolo,Sambri, Letizia
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p. 3489 - 3496
(2008/09/19)
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- Design and synthesis of compartmental ligands and their complexes for the production of catalytic antibodies
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The synthesis and coordination properties of mixed N,O-compartmental ligands is described. Macrocyclic ligands 8 and 15 were designed to mimic transition-state analogs for the production of catalytic antibodies for C-H activation reactions. Reaction of 8
- Duclos, Severine,Stoeckli-Evans, Helen,Ward, Thomas R.
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p. 3148 - 3161
(2007/10/03)
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