Oxidative single-electron transfer-catalyzed tandem reactions consisting of a conjugate addition and a radical cyclization are reported, which incorporate the mandatory terminal oxidant as a functionality into the product.

A new method for alcohol oxidation using TEMPO or AZADO in conjunction with BF3·OEt2 or LiBF4 as precatalysts and tert-butyl nitrite as a stoichiometric oxidant has been developed. The system is based on a NO(+)/NO· pair for nitroxide reoxidation under anaerobic conditions. This allows the simple, high-yielding conversion of various achiral and chiral alcohols to carbonyl compounds without epimerization and no formation of nonvolatile byproducts.

International audienceNovel telechelic primary diols and diacrylates based on vinylidene fluoride (VDF) and perfluoromethyl vinyl ether (PMVE) were synthesized as precursors of original photocrosslinkable networks. First, poly(VDF-co-PMVE) copolymers were generated by controlled radical copolymerization of VDF and PMVE in the presence of -diiodoperfluorobutane, leading to copolymers with molecular weight ranging between 1500 and 7000 g.mol-1. Then, two major approaches were applied to obtain telechelic poly(VDF-co-PMVE) diols as precursors for bis(acrylate)s containing spacers of various lengths between hydroxyl or ester functions and the poly(VDF-co-PMVE) oligomeric chain. The first strategy involved quantitative ethylene end-capping of telechelic diiodo poly(VDF-co-PMVE) copolymer and subsequent hydrolysis to form diols with ethylene spacers (C2) between -OH moieties and the fluorinated oligomeric chain. The second approach to obtain fluorinated diols involved the radical addition of telechelic diiodo poly(VDF-co-PMVE) copolymer onto allyl alcohol to obtain bis(iodohydrine), the iodine atoms of which were further reduced to yield fluorinated diols (85 % yield) that bear three methylene groups (C3) as the spacer between -OH moieties and the fluorinated chain. Acryloylation of C2 diol was optimized for various acrylating agents and catalysts and led to 80 % yield. The acryloylation of C3 diols was carried out using acryloyl chloride and taking into account the results from C2 optimization (90 % yields). UV curing of C2 and C3 telechelic bis(acrylate)s in the presence of two different photoinitiators (Darocur® 1173 and Irgacure® 819) led to crosslinked films. UV irradiation was performed using two different machines: Fusion UV system Inc., USA and UV-system of Applied Curing Technology Ltd., UK at ETC of DuPont Performance Elastomers, Geneva. It was found that Darocur® 1173 can be successfully used as photo initiator for thin films (less than 0.25 mm) while for thicker films (more than 0.75 mm to 1.5 mm) Irgacure® 819 is more efficient. The gel contents, flexibilities (via the assessment of their glass transition temperatures that ranged between -55 and -30 °C) and thermal behavior (their 10 wt.% losses were ranging between 300 and 350 °C, under air) were investigated. The thermal properties of the resulting materials were better than those of the telechelic poly(VDF-co-PMVE) copolymeric precursors. The UV activated networks of diacrylated fluorooligomers with C3 spacers formed better pale yellow cross-linked films compared to those with C2 spacers