- Borane-induced radical reduction of 1-alkenyl- and 1-alkynyl-λ3-iodanes with tetrahydrofuran
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Exposure of 1-alkenyl(phenyl)- and 1-alkynyl(phenyl)-λ3-iodanes to THF at room temperature in the presence of a catalytic amount of trialkylborane results in smooth reduction to give 1-iodo-1-alkenes and 1-iodo-1-alkynes as major products, respectively. The key step in the reductions probably involves a single-electron transfer from α-tetrahydrofuryl radical to the λ3-iodanes, which generates the labile [9-I-2] iodanyl radicals.
- Ochiai, Masahito,Tsuchimoto, Yoshimi,Hayashi, Takanori
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p. 5381 - 5384
(2007/10/03)
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- Formamides undergo in-plane bimolecular nucleophilic vinylic substitutions (S(N)2) by the reaction with (E)-alkenyl(phenyl)iodonium tetrafluoroborates: Stereoselective synthesis of (Z)-vinyl formates
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Reported for the first time is the stereoselective synthesis of (Z)-vinyl formates, which involves in-plane bimolecular nucleophilic vinylic substitutions of (E)-β-alkylvinyl(phenyl)iodonium tetrafluoroborates with formamides.
- Ochiai, Masahito,Yamamoto, Shinji,Sato, Koichi
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p. 1363 - 1364
(2007/10/03)
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- Studies on the Thermal Conversion of Long-chain Alkynes at High Temperatures in the Gas Phase
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In the gas phase pyrolysis of long-chain alkynes C5 to C9 at 773 to 873 K, a remarkable portion of molecular reaction (retro-ene analogous decompositions as well as cycloisomerizations of the parent alkynes to cyclopentenes alkylated in 3-position) takes place besides the thermal conversion of the starting compounds via radical chain processes.The different products were separated by GC and the main products identified by means of different methods.The mechanisms of formation of the major products are discussed.
- Ondruschka, B.,Zimmermann, G.,Ziegler, U.,Kopinke, F.-D.,Teuber, M.
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p. 273 - 284
(2007/10/02)
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- On 1.2-Shift Reactions and C-H-Insertions of Acyclic Alkylidene Carbenes
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Two series of acyclic terminal vinyl bromides (1...4 and 5...7) were tested in the reaction with potassium tert-butoxide as precursors of alkylidene carbenes.As expected 1 up to 4 only give 1-alkynes whereas the 2-methylated vinyl bromides 5, 6 and 7 yield 1-methylated cyclopentenes predominantly besides 2-alkynes.The formation of cyclopentenes indicates a reaction route via alkylidene carbenes and 1,5-C-H-insertion reactions, that of 2-alkynes is convincing evidence for 1,2-alkyl shift reactions in 2-methyl substituted alkylidene carbenes.The selectivity of 1,5-C-H-insertion depends on the degree of alkyl substitution of the C-5-atom.At 240 deg C the selectivity is 1deg:2deg:3deg ca. 1:54:240.
- Ondruschka, Bernd,Remmler, Matthias,Zimmermann, Gerhard,Krueger, Christian
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