- One-pot practical preparation of novel propargylic aryl and heteroaryl sulfides and sulfones
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A one-pot preparation of functionalized propargylic aryl and hetero aryl sulfides from primary alcohols and thiols through the formation of the corresponding iodide or tosylate compounds is presented. The corresponding sulfones are prepared by subsequent
- Bonini, Carlo,Chiummiento, Lucia,Videtta, Valeria
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- Streamlined Catalytic Enantioselective Synthesis of α-Substituted β,γ-Unsaturated Ketones and Either of the Corresponding Tertiary Homoallylic Alcohol Diastereomers
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A widely applicable, practical, and scalable strategy for efficient and enantioselective synthesis of β,γ-unsaturated ketones that contain an α-stereogenic center is disclosed. Accordingly, aryl, heteroaryl, alkynyl, alkenyl, allyl, or alkyl ketones that contain an α-stereogenic carbon with an alkyl, an aryl, a benzyloxy, or a siloxy moiety can be generated from readily available starting materials and by the use of commercially available chiral ligands in 52-96% yield and 93:7 to >99:1 enantiomeric ratio. To develop the new method, conditions were identified so that high enantioselectivity would be attained and the resulting α-substituted NH-ketimines, wherein there is strong CN → B(pin) coordination, would not epimerize before conversion to the derived ketone by hydrolysis. It is demonstrated that the ketone products can be converted to an assortment of homoallylic tertiary alcohols in 70-96% yield and 92:8 to >98:2 dr - in either diastereomeric form - by reactions with alkyl-, aryl-, heteroaryl-, allyl-, vinyl-, alkynyl-, or propargyl-metal reagents. The utility of the approach is highlighted through transformations that furnish other desirable derivatives and a concise synthesis route affording more than a gram of a major fragment of anti-HIV agents rubriflordilactones A and B and a specific stereoisomeric analogue.
- Pozo, Juan Del,Zhang, Shaochen,Romiti, Filippo,Xu, Shibo,Conger, Ryan P.,Hoveyda, Amir H.
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supporting information
p. 18200 - 18212
(2020/11/02)
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- Rhodium-catalyzed hydroformylation of 1,1-disubstituted allenes employing the self-assembling 6-DPPon system
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Abstract A rhodium-catalyzed hydroformylation of 1,1-disubstituted allenes is reported. Using a RhI/6-DPPon catalyst system, one can obtain β,γ-unsaturated aldehydes in high regio- and chemoselectivity. The Z-configured product is formed with up to >95% selectivity when unsymmetrically 1,1-disubstituted allenes are submitted to the reaction conditions. This is the first time that these interesting building blocks are accessible by hydroformylation of allenes. The utility of this methodology is demonstrated by further transformations of one of the obtained products. β,γ-Unsaturated aldehydes are obtained by a rhodium-catalyzed hydroformylation of 1,1-disubstituted allenes. For unsymmetrically 1,1-disubstituted allenes the Z-configured product is formed in up to about 95% selectivity. This is the first time that these building blocks are accessible by hydroformylation of allenes. The utility of this methodology is demonstrated by further transformations of one of the obtained products.
- K?pfer, Alexander,Breit, Bernhard
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p. 6913 - 6917
(2015/06/08)
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- Fused ring aziridines as a facile entry into triazole fused tricyclic and bicyclic heterocycles
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The intramolecular dipolar cycloaddition of an azide with an alkyne has provided a useful entry into triazole fused tricyclic heterocycles containing both the triazole ring and the oxazolidin-2-one ring system. The requisite azido-alkynes have been prepared via a two-step sequence from fused ring aziridines. A series of 6-12 membered rings containing both the oxazolidinone and triazole rings have been prepared. These ring systems have been designed as conformationally restrained analogs of RNA-binding oxazolidinones. The Royal Society of Chemistry 2012.
- Fang, Fang,Vogel, Megan,Hines, Jennifer V.,Bergmeier, Stephen C.
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scheme or table
p. 3080 - 3091
(2012/05/07)
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- Amplification of anti-diastereoselectivity via Curtin-Hammett effects in ruthenium-catalyzed hydrohydroxyalkylation of 1,1-disubstituted allenes: Diastereoselective formation of all-carbon quaternary centers
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Under the conditions of ruthenium-catalyzed transfer hydrogenation, 1,1-disubstituted allenes la-c and alcohols 2a-g engage in redox-triggered generation of allylruthenium-aldehyde pairs to form products of hydrohydroxyalkylation 3a-g, 4a-g, and 5a-g with complete branched regioselectivity. By exploiting Curtin-Hammett effects, good to excellent levels of anti-diastereoselectivity (4:1 to >20:1) are obtained. Thus, all carbon quaternary centers are formed in a diastereoselective fashion upon carbonyl addition from the alcohol oxidation level in the absence of premetalated nucleophiles or stoichiometric byproducts. Exposure of allene lb to equimolar quantities of alcohol 2a and aldehyde 6b under standard reaction conditions delivers adducts 4a and 4b in a 1:1 ratio. Similarly, exposure of allene lb to equimolar quantities of aldehyde 6a and alcohol 2b provides adducts 4a and 4b in an identical equimolar ratio. Exposure of allene lb to d2-p- nitrobenzyl alcohol, deuterio-2a, under standard reaction conditions delivers the product of hydrohydroxyalkylation, deuterioAa, which incorporates deuterium at the carbinol position (>95% 2H) and the interior vinylic position (34% H). Competition experiments involving exposure of allene lb to equimolar quantities of benzylic alcohols 2a and deuterio-2a reveal no significant kinetic effect. The collective data corroborate rapid, reversible alcohol dehydrogenation, allene hydrometalation, and (E)-, (Z)-isomerization of the transient allylruthenium in advance of turnover-limiting carbonyl addition. Notably, analogous allene-aldehyde reductive C-C couplings employing 2-propanol as the terminal reductant display poor levels of anti-diastereoselectivity, suggesting that carbonyl addition is not turnover-limiting in reactions conducted from the aldehyde oxidation level.
- Zbieg, Jason R.,Mclnturff, Emma L.,Leung, Joyce C.,Krische, Michael J.
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supporting information; experimental part
p. 1141 - 1144
(2011/04/16)
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- Synthesis of tricyclic fused 3-aminopyridines through intramolecular Coi-catalyzed [2+2+2] cycloaddition between ynamides, nitriles, and alkynes
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The first [2+2+2] cocyclizations between ynamides, nitriles, and alkynes are reported. They open a new access to unprecedented nitrogen-containing heterocycles of type 2-trimethylsilyl-3-aminopyridines. Such frameworks, which can be found in various compo
- Garcia, Pierre,Moulin, Solenne,Mielo, Yves,Leboeuf, David,Gandon, Vincent,Aubert, Corinne,Malacria, Max
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scheme or table
p. 2129 - 2139
(2009/09/06)
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