“…These results showed that the group transfer reaction occurred preferentially by the less-hindered face of the intermediate radical in the case of the xanthate 1 . Precedents for high trans selectivity were observed previously during the course of the iodine-atom-transfer addition involving iodofluoroacetate derivatives and cyclic alkenes. , 3 Xanthate Group Transfer to Cyclic Alkenes…”
A two-step preparation of 2,3-trans disubstituted tetrahydrofuran derivatives is reported from S-alkyl dithiocarbonates. The study of the group transfer reaction from xanthates and alkenes afforded intermediate S-alkyl dithiocarbonates. From 2,3-dihydrofuran derivatives, the displacement of the resulting anomeric xanthates with various nucleophiles in the presence of Lewis acid allowed the formation of new carbon-carbon and carbon-heteroatom bonds. This strategy was illustrated by a two-step synthesis of a precursor of modified 2'-beta-C-branched nucleoside analogues.
“…These results showed that the group transfer reaction occurred preferentially by the less-hindered face of the intermediate radical in the case of the xanthate 1 . Precedents for high trans selectivity were observed previously during the course of the iodine-atom-transfer addition involving iodofluoroacetate derivatives and cyclic alkenes. , 3 Xanthate Group Transfer to Cyclic Alkenes…”
A two-step preparation of 2,3-trans disubstituted tetrahydrofuran derivatives is reported from S-alkyl dithiocarbonates. The study of the group transfer reaction from xanthates and alkenes afforded intermediate S-alkyl dithiocarbonates. From 2,3-dihydrofuran derivatives, the displacement of the resulting anomeric xanthates with various nucleophiles in the presence of Lewis acid allowed the formation of new carbon-carbon and carbon-heteroatom bonds. This strategy was illustrated by a two-step synthesis of a precursor of modified 2'-beta-C-branched nucleoside analogues.
“…It was found that perfluorinated carboxylic and sulfonic acids containing chains of four or less perfluorinated carbon atoms do not bioaccumulate in the human body and are not biopersistent. In order to find environmentally friendly and nontoxic alternative fluoropolymers to avoid the challenges associated with PFOA, a series of fluorinated comblike polymers containing the shorter and nonbiopersistant perfluorobutyl group as the fluorinated component of the side chains, called as C4 polymers, have been prepared starting from perfluorobutyl iodide. − The new compounds are analogous to conventional textile-treating materials and are processed and characterized by similar methods. The properties of the C4 polymers are tuned by changing the “spacers” between the polymer backbones and the perfluorinated groups of the side chains.…”
The degradation of stain-resistant coating materials leads to the release of biopersistent perfluorooctanoic acid (PFOA) to the environment. In order to find the environmentally friendly substitutes, we have designed and synthesized a series of nonbiopersistant fluorinated polymers containing perfluorobutyl groups in the side chains. The surface properties of the new coating materials were characterized by static and dynamic contact angle measurements. The new coating materials demonstrate promising hydrophobic and oleophobic properties with low surfaces tensions. The wetting properties and surface structure of the polymers were tuned by varying the "spacer" structures between the polymer backbones and the perfluorinated groups of the side chains. The relationship between orientations of the fluorinated side chains and performances of polymer surfaces were further investigated by near-edge X-ray fine absorption structure (NEXAFS) experiments and differential scanning calorimetry (DSC).
“…Similarly, the CF 2 CO 2 R group is important because it allows the potential for further functionalization once it is incorporated . Previous halo, carboalkoxydifluoromethylations have been limited to the use of ethyl or methyl halo- or xantho-difluoroacetates (XCF 2 CO 2 R) as precursors of the carboalkoxydifluoromethyl radical, where X = Br, I, or SCOSR, with these reactions proceeding via atom transfer radical addition (ATRA) processes (Scheme ) …”
Difluoromethyl and carbomethoxydifluoromethyl radicals were generated from their respective sulfonyl chlorides under mild, metal-free conditions leading to efficient atom transfer radical additions (ATRA) to unactivated alkenes to form chloro, difluoromethylated and chloro, carbomethoxydifluoromethylated products.
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