The Pressure Effect on the 1,5-Sigmatropic Hydrogen Shift of Tropylidene Derivative, 3,3-Diphenyl-3,3<i>a</i>-dihydrocyclohepta[<i>b</i>]furan-2-one
作者:Shigeru Sugiyama、Hitoshi Takeshita
DOI:10.1246/cl.1986.1203
日期:1986.7.5
The 1,5-sigmatropy of 3,3-diphenyl-3,3a-dihydrocyclohepta[b]furan-2-one was examined in dibutyl ether to 1600 bar at 130 °C. The rearrangement was slightly accelerated with pressure, and was different to the pressure effect of 1,5-sigmatropy of cyclopentadienes. The activation volume was in the range of the concerted process, but its transition state was as loose as those biradical-like.
3,3-二苯基-3,3a-二氢环庚烷[b]呋喃-2-酮的 1,5-σ 向性在二丁醚中于 130 °C 下检测到 1600 bar。重排在压力下略有加速,与环戊二烯的1,5-sigmatropy的压力效应不同。活化体积在协同过程范围内,但其过渡态与双自由基一样松散。
Tropone Is a Mere Ketone for Cycloadditions to Ketenes
Tropone (1) reacts with ketenes 2 to yield [8+2] cycloadducts, the γ-lactones 3. The concerted [8+2] cycloaddition path is formally symmetry-allowed, but we established that it is unfavorable. Careful low-temperature NMR (1H, 13C, and 19F) spectroscopies of the reaction of diphenyl ketene (2b) or bis(trifluoromethyl) ketene (2c) with tropone (1) allowed the direct detection of a β-lactone intermediates