Iron(II)/copper(I)-mediated stereoselective carbozincation of ynamides. One-pot synthesis of alpha-allyl-tetrasubstituted-enamides

International audienceThe iron(II) chloride- and copper(I) iodide-mediated carbozincation of a panel of substituted ynamides is described in this article. The reaction is totally regio- and stereoselective. Experiments showed that the reaction mediated with Fe(II) was more substrate dependent than the reaction performed with Cu(I). Interestingly, in the presence of allylbromide, stereoselective carboallylation can be achieved for the first time in a one-pot procedure, leading to skipped dienamides

Novozym 435-catalyzed synthesis of polyetheramides from amino-esters, or diesters and diamines built on ethylene- and diethylene- glycol moieties

International audienceThe optimization of CAL-B-promoted (Novozym 435) A/B and AA/BB type polymerizations leading topolyetheramides, from amino ethylesters or diethyl esters and diamines based on ethylene- ordiethylene-glycol moieties, is disclosed herein. From these preliminary experiments it became obviousthat it is of prime importance: to avoid the presence of water by carefully drying the enzyme prior to use;to eliminate ethanol from the reaction medium, by working under reduced pressure in order to drive theamidation reaction forward; to select an appropriate high boiling solvent, the best choice being diphenylether. Under such experimental conditions, polyetheramides were obtained in 70e80% yield with anaverage degree of polymerization (DPn) up to 17

Speeding-up enzyme-catalyzed synthesis of polyamides using omega-amino-alpha-alkoxy-acetate as monomer

International audienceThe design of omega-amino-alpha-alkoxy-acetate as monomer enables to dramatically speed up the formation of polyamides catalyzed by the supported lipase B of Candida antarctica. Only 30 min are needed to reach 93% conversion whereas 240 h are necessary to observe the same level of conversion with a monomer devoided of an oxygen atom in position beta relative to the electrophilic carbonyl group. Yields, Mn, Mw, DPn and PDI reach very good values for an enzymatic synthesis of polyamides. (C) 2013 Elsevier Ltd. All rights reserved

CAL-B catalyzed synthesis of chiral polyamides

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Aminomethylation of Michael Acceptors: Complementary Radical and Polar Approaches Mediated by Dialkylzincs

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Intermolecular Addition of Carbon-Centered Radicals to Ynamides. A Regio- and Stereoselective Route to Persubstituted α-Iodo-enamides

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Aminomethylation of Michael Acceptors: Complementary Radical and Polar Approaches Mediated by Dialkylzincs

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Investigation of UV Light-Promoted Synthesis of α-Sulfonyl Amides from N -Sulfonyl Ynamides

International audienceUV Light-promoted synthesis of α-sulfonyl amides from N-sulfonyl ynamides without any additives is reported. The reaction proceeds through a radical chain mechanism involving the photo-induced cleavage of the nitrogen-sulfur bond, addition of electrophilic sulfonyl radical to the triple bond of the ynamide followed by beta-fragmentation of the sulfonyl group leading to a ketenimine hydrated upon work-up. This highly efficient rearrangement leads, after acidic treatment, to a wide range of α-sulfonyl amides in high yields

Ynamides in Radical Reactions: A Route to Original Persubstituted 2‑Aminofurans

Mn(OAc)3/Cu(OAc)2-mediated reaction between ynamides, derived from oxazolidone or 3-methylindole carboxylate, and cyclic α-dicarbonyl radicals led to the one-pot synthesis of 2-aminofurans. The transformation involves addition of the α-dicarbonyl radical to ynamide, oxidation to ketene-iminium, and polar cyclization steps to provide original persubstituted 2-aminofurans in good to excellent yields. This work represents the first radical route for the synthesis of furans from ynamides

Theoretical Support for the Involvement of a Radical Pathway in the Formation of Allenylzincs from Propargyl Iodides and Dialkylzincs: Influence of Zinc Coordination

Propargyl iodides are good precursors for allenylzincs via reaction with diethylzinc, even in nondegassed medium. These reactions proceed via zinc/iodine exchange. Owing to the previously reported detection of propargyl radical by ESR experiments, in this process a radical mechanism was suspected. Calculations of the C–Zn BDEs in allenyl- and propargylzinc species were performed with the CBS-QB3 method to demonstrate that propargyl radicals could undergo homolytic substitution at zinc. The stabilization of allenylzinc derivatives by chelation, made possible by the selection of appropriate ortho-substituted 3-phenylalkynyl iodides as precursors, was shown to influence the regioselectivity of their addition to aldehydes and ketones. The more stabilized the chelated allenylzinc intermediate, the higher the ratio of homopropargylic alcohols