- Ligand-Controlled Regiodivergent Catalytic Amidation of Unactivated Secondary Alkyl Bromides
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A regiodivergent Ni-catalyzed amidation of unactivated secondary alkyl bromides is described. The site-selectivity of the amidation event is dictated by subtle differences on the ligand backbone, allowing introduction of the amide function at either the original sp3 carbon-halide bond or at distal sp3 C-H sites within an alkyl side-chain via chain-walking scenarios.
- Tortajada, Andreu,Menezes Correia, Jose Tiago,Serrano, Eloisa,Monleón, Alicia,Tampieri, Alberto,Day, Craig S.,Juliá-Hernández, Francisco,Martin, Ruben
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p. 10223 - 10227
(2021/08/24)
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- Photoinduced, copper-catalyzed alkylation of amides with unactivated secondary alkyl halides at room temperature
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The development of a mild and general method for the alkylation of amides with relatively unreactive alkyl halides (i.e., poor substrates for S N2 reactions) is an ongoing challenge in organic synthesis. We describe herein a versatile transition-metal-catalyzed approach: in particular, a photoinduced, copper-catalyzed monoalkylation of primary amides. A broad array of alkyl and aryl amides (as well as a lactam and a 2-oxazolidinone) couple with unactivated secondary (and hindered primary) alkyl bromides and iodides using a single set of comparatively simple and mild conditions: inexpensive CuI as the catalyst, no separate added ligand, and C-N bond formation at room temperature. The method is compatible with a variety of functional groups, such as an olefin, a carbamate, a thiophene, and a pyridine, and it has been applied to the synthesis of an opioid receptor antagonist. A range of mechanistic observations, including reactivity and stereochemical studies, are consistent with a coupling pathway that includes photoexcitation of a copper-amidate complex, followed by electron transfer to form an alkyl radical.
- Do, Hien-Quang,Bachman, Shoshana,Bissember, Alex C.,Peters, Jonas C.,Fu, Gregory C.
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supporting information
p. 2162 - 2167
(2014/03/21)
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- XtalFluor-E, an efficient coupling reagent for amidation of carboxylic acids
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Amides were produced from carboxylic acids and amines by using XtalFluor-E as an activator. Even poorly reactive carboxylic acids can be transformed to amides. In addition, optically active amines and/or carboxylic acids were not epimerized/racemized during the process.
- Orliac, Aurélie,Gomez Pardo, Domingo,Bombrun, Agnès,Cossy, Janine
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supporting information
p. 902 - 905
(2013/03/29)
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- Synthesis of amides and lactams in supercritical carbon dioxide
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(Chemical Equation Presented) Supercritical carbon dioxide can be employed as an environmentally friendly alternative to conventional organic solvents for the synthesis of a variety of carboxylic amides. The addition of amines to ketenes generated in situ via the retro-ene reaction of alkynyl ethers provides amides in good yield, in many cases with ethylene or isobutylene as the only byproducts of the reaction. Reactions with ethoxy alkynes are performed at 120-130°C, whereas tert-butoxy derivatives undergo the retro-ene reaction at 90°C. With the exception of primary, unbranched amines, potential side reactions involving addition of the amines to carbon dioxide are not competitive with the desired C-N bond-forming reaction. The amide synthesis is applicable to the preparation of β-hydroxy and β-amino amide derivatives, as well as amides bearing isolated carbon-carbon double bonds. Preliminary experiments aimed at developing an intramolecular variant of this process to afford macrolactams suggest that the application of CO2/co-solvent mixtures may offer advantages for the synthesis of large-ring compounds.
- Mak, Xiao Yin,Ciccolini, Rocco P.,Robinson, Julia M.,Tester, Jefferson W.,Danheiser, Rick L.
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experimental part
p. 9381 - 9387
(2010/03/04)
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- Acyl transfer catalysis with 1,2,4-Triazole anion
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1,2,4-Triazole anion has been identified as an active acyl transfer catalyst suitable for the aminolysis and transesterification of esters.
- Yang, Xing,Birman, Vladimir B.
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supporting information; experimental part
p. 1499 - 1502
(2009/09/06)
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- Tighter ion pair effect and scale-up study in microwave assisted aminolysis of enolizable esters using potassium tert-butoxide (t-BuOK)
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The tighter ion pair effect and scale-up study in aminolysis of enolizable esters using potassium tert-butoxide (t-BuOK) under microwave irradiations is described. This method provides synthetic advantages in terms of reaction time, product yields, eco-friendly environment and scale-up feasibility over the conventional heating method.
- Polshettiwar, Vivek,Kaushik
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p. 773 - 777
(2007/10/03)
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- Self-folding cavitands of nanoscale dimensions
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New types of resorcinarene-based nanoscale container molecules 2 and 3 are described. They feature reversibly folding unimolecular cavities of nanoscale dimensions and ~800 A3 internal volume; they are among the largest synthetic unimolecular hosts prepared to date. Two seams of intramolecular hydrogen bonds, provided by 12 secondary amides, control the guest uptake and release. The hydrogen bonds resist the unfolding of the host and increase the energetic barrier to guest exchange. Exchange is slow on the NMR time scale (room temperature), and kinetically stable complexes result. The direct observation of bound species and the stoichiometry of the complexes are reported. A series of adamantyl and cyclohexyl guests 11-19 of various shapes and lengths were prepared and used to estimate the hosts' capacities. Compound 2 exists in an S-shaped conformation and its two cavities act independently; each half of host 2 formed kinetically stable complexes with either two identical or different guest molecules. The C-shaped host 3 accommodates rigid and long guests with association constants (K(a)) between 500 ± 50 M-1 (-ΔG295 = 3.6 ± 0.1 kcal mol-1) and 270 ± 100 M-1 (-ΔG295 = 3.2 ± 0.2 kcal mol-1) for adamantyl derivatives. With the more flexible and/or shorter guests, fast exchange between the free and complexed guest species was observed at room and higher temperatures (in toluene-d8). Guest exchange rates of the new hosts are considerably faster than rates seen with typical hemicarceplexes but slower than those of other open-ended cavitands.
- Lucking,Tucci,Rudkevich,Rebek Jr.
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p. 8880 - 8889
(2007/10/03)
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- A mild and efficient procedure for the preparation of acid chlorides from carboxylic acids
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Various carboxylic acids are converted into the corresponding acid chlorides by treatment with trichloroacetonitrile and triphenylphosphine in methylene chloride at room temperature. Aryl acids show higher reactivity than alkyl acids under the conditions.
- Jang, Doo Ok,Park, Doo Jin,Joonggon, Kim
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p. 5323 - 5326
(2007/10/03)
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