- Efficient synthesis of 16-28 membered macrocyclic crown amides via ring closing metathesis
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Ring closing metathesis of suitable diamides containing 1,ω-dienes led to efficient synthetic approaches towards macrocylic polyoxadiamides 1-18 with 16-28 membered ring sizes in good to excellent yields using Grubbs' catalyst.
- Ibrahim, Yehia A.,Behbehani, Haider,Ibrahim, Maher R.,Malhas, Rana N.
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- Smiles rearrangements in Ugi- and Passerini-type couplings: New multicomponent access to O- and N-arylamides
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(Chemical Equation Presented) The use of Smiles rearrangement in Ugi- and Passerini-type couplings with electron-deficient phenols allows very straightforward multicomponent formation of O-aryl- and N-arylamides. Best yields were observed with the highly activated o- and p-nitrophenols, salicylic derivatives giving adducts in lower yields. The scope of these new reactions is further increased by the successful couplings of heterocyclic phenols such as hydroxypyridines and hydroxypyrimidines.
- El Kaim, Laurent,Gizolme, Marie,Grimaud, Laurence,Obie, Julie
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- Electrochemical Chalcogenation of β,γ-Unsaturated Amides and Oximes to Corresponding Oxazolines and Isoxazolines
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The current report represents a transition-metal-free synthesis of oxazoline and isoxazoline derivatives by a tandem electro-oxidative chalcogenation-cyclization process. Both C?Se and C?S bond-forming protocols were developed without using any external oxidant and the reaction was performed at room temperature, open to the air. Using this methodology, 29 substituted oxazoline and 16 substituted isoxazoline derivatives were synthesized with up to 91% isolated yield. (Figure presented.).
- Baidya, Mrinmay,De Sarkar, Suman,Mahanty, Kingshuk,Maiti, Debabrata,Mallick, Samrat
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supporting information
(2020/02/04)
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- Fast synthesis of amides from ethyl salicylate under microwave radiation in a solvent-free system
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In this study, amide bond formation, one of the most important reactions in organic chemistry, it was evaluated using ethyl salicylate and ten different primary amines. Under the optimized experimental conditions, i.e. 60 °C, hexane, phenylboronic acid-PBA (15 mol%), boric acid-BA (15 mol%) or without catalyst-WC, using a hot-plate for 24 h, amides were obtained in excellent isolated yields (WC, 77-94% to S-Aa-Ad; PBA, 11-94% to S-Ae-Aj; and BA, 28-90% to S-Ae-Aj). The reaction employing CAL-B also permitted a moderate conversion for the production of amides S-Ae-Aj (3-42%). However, in our efforts to reduce the amide synthesis time (24 h), the reactions were performed in the presence of microwave-MW radiation using a free-solvent system [60 °C, PBA (15 mol%) or WC], which reduced the time of the reaction by 32-fold (45 min) and afforded nine amides (S-Aa-Ah and S-Aj) in 80-99% isolated yield and S-Ai in 23% yield. A cytotoxicity assay demonstrated that the amide S-Ag was capable of inhibiting four human tumor cell lines (MCF-7, HCT116, HepG2, and HL-60) with an IC50 ranging from 8.68 to 17.57 μg mL-1. In this study, MW radiation provided an attractive way for faster reactions, improved yields, and cleaner reactions, as well as the synthesis of amide S-Ag with cytotoxic activity.
- Lima, Rafaely N.,Silva, Valdenizia R.,De Santos, Luciano,Bezerra, Daniel P.,Soares, Milena B. P.,Porto, André L. M.
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p. 56566 - 56574
(2017/12/26)
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