- Transformation of β-chalcogeno alkenylboranes into tetrasubstituted olefins
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In view of generating trisubstituted vinylic chalcogen derivatives, β-chalcogeno alkenylboranes generated through the chalcogen electrophile induced rearrangements of 1-alkynyltrialkyl borates have been subjected to Suzuki-Miyaura coupling and to boron to copper transmetalation followed by alkylation. Some of the trisubstituted vinyl sulfides obtained by this latter strategy have been converted efficiently into the title olefins through the NiCl2(dmpe) catalyzed coupling with various Grignard reagents.
- Gerard, Julien,Hevesi, László
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p. 367 - 381
(2007/10/03)
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- Chalcogen electrophile induced rearrangement of 1-alkynyltrialkyl borates: Controlled syntheses of trisubstituted olefins from 1-alkynes
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The reaction of 1-alkynyltrialkyl borates with sulfenyl, selenenyl and tellurenyl halides produces β-chalcogeno alkenylboranes in good yields, with a cis relationship between the boron and the chalcogen moities. Protodeborylation of these compounds by acetic acid, or by a transmetalation-protonolysis sequence, leads to vinyl chalcogenides, which can be converted to alkenes by means of a nickel catalyzed coupling with Grignard reagents. Since the last two steps occur with retention of the stereochemistry, the overall sequence represents a highly regio- and stereoselective olefin synthesis.
- Gerard, Julien,Hevesi, László
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p. 9109 - 9121
(2007/10/03)
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- Vinylborane and vinyichalcogenide mediated syntheses of tri- and tetrasubstituted olefins from 1-alkynes
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The title olefins have been prepared with high regio- and stereocontrol from 1-alkynes through vinyl boranes 1 vinyl chalcogenides; the reaction sequences involved protonolysis or transmetallation - alkylation of the boranes followed by an Ni(0) catalyzed coupling reaction.
- Gerard, Julien,Bietlot, Emerance,Hevesi, Laszlo
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p. 8735 - 8738
(2007/10/03)
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- Preparation of olefins and acetylenes via reductive elimination with Sml2-HMPA
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Reaction of β-hydroxy or acetoxy sulfones with Sml2 in the presence of HMPA caused effectively reductive elimination to provide olefins. Treatment of enol phosphates, readily synthesized from β-hydroxy sulfones via keto sulfones, under the same conditions efficiently produced mono- and disubstituted acetylenes.
- Ihara, Masataka,Suzuki, Shuichi,Taniguchi, Takahiko,Tokunaga, Yuji,Fukumoto, Keiichiro
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p. 9873 - 9890
(2007/10/02)
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