- Thermal rearrangements of spiro[2.4]hepta-1,4,6-trienes
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Thermolysis of spiro[2.4]hepta-1,4,6-triene (1a) at 50°C yielded bicyclo[3.2.0]hepta-1,3,6-triene (5), which dimerized in two different fashions to form cyclobutanes. The 1,2-dimethyl and 1-propyl derivatives of la also rearranged at 50°C, but at a faster rate, each yielding a pair of cyclobutane dimers. The structures of these symmetrical dimers were investigated by 1D and 2D NMR and NOE difference spectroscopy. Ab initio calculations indicated that the two strained olefins la and 5 had comparable energies about 50 kcal/mol lower than norborna-1(7),2,5-triene, which was thus excluded as a reaction intermediate.
- Billups,Saini, Rajesh K.,Litosh, Vladislav A.,Alemany, Lawrence B.,Wilson, William K.,Wiberg, Kenneth B.
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- Solvent interception, heterocyclization and desilylation upon NBS-induced sulfamidation of trimethyl(vinyl)silane
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The reaction of trimethyl(vinyl)silane with sulfonamides in the presence of N-bromosuccinimide was shown to proceed regioselectively in methylene chloride under mild conditions and led to the products of bromosulfamidation in up to 88% yield. The obtained adducts undergo base-promoted dehydrobromination to give 2-trimethylsilyl-N-sulfonyl aziridines in a close to quantitative yield. In the reaction with trifluoromethanesulfonamide in acetonitrile or tetrahydrofuran, the Ritter-type (solvent-interception) products were obtained and converted to 1-triflyl-2-methyl-5-(trimethylsilyl)-2-imidazoline or 4-triflyl-3-(trimethylsilyl)-1,4-oxazocane in almost quantitative yield.
- Astakhova, Vera V.,Moskalik, Mikhail Yu.,Shainyan, Bagrat A.
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