to the cuneane radicalcation (2*+) and for the C-C bond fragmentation to the secocubane-4,7-diyl radicalcation (10*+) are virtually identical (deltaH0++ = 7.8 and 7.9 kcalmol(-1), respectively). The low-barrier rearrangement of 10*+ to the more stable syn-tricyclooctadiene radicalcation 3*+ favors the fragmentation pathway that terminates with the cyclooctatetraene radicalcation 6*+. Experimental
作者:Steffen L. Woltering、Przemyslaw Gawel、Kirsten E. Christensen、Amber L. Thompson、Harry L. Anderson
DOI:10.1021/jacs.0c05308
日期:2020.8.5
in quantitative dimerization via [2+2] cycloaddition to form a [3]-ladderane; irradiation of this ladderane at 250 nm generates a dihydrotriphenylene, which can be oxidized easily to a triphenylene. Irradiation of the indane-based MAE at 350 nm in the presence of traces of oxygen forms an endoperoxide and a bisepoxide. Both MAEs have been incorporated into rotaxanes via copper-mediated active metal
聚炔聚轮烷的合成需要大量的光不稳定掩蔽炔烃等价物 (MAE),作为绝缘分子线和碳炔的线性聚合物同素异形体的稳定形式。我们合成了一种基于菲的新型 MAE,并将其与基于茚满的 MAE 进行了比较。在不同波长(250 nm 和 350 nm)下研究了模型化合物的光化学暴露,并通过核磁共振光谱和 X 射线晶体学鉴定了关键产物。250 nm 的紫外线照射导致两种 MAE 的暴露。菲体系在 350 nm 下的辐照导致通过 [2+2] 环加成形成 [3]-ladderane 的定量二聚化;这种梯烷在 250 nm 下的辐射会产生二氢苯并苯,它可以很容易地被氧化成苯并苯。在痕量氧存在下以 350 nm 辐照茚满基 MAE 形成内过氧化物和双环氧化物。两种 MAE 均已通过铜介导的活性金属模板 Glaser 或 Cadiot-Chodkiewicz 偶联结合到轮烷中。轮烷的身份通过核磁共振光谱和质谱确认。菲
Stereoselective 1,4 bromination of semibullvalene and tri-n-butyltin hydride reduction of the dibromide
作者:Leo A. Paquette、Gary H. Birnberg、Jon Clardy、Bruce Parkinson
DOI:10.1039/c39730000129
日期:——
Bromination of semibullvalene proceeds with stereoselective cis,exo-1,4-addition in contrast to bullvalene where kinetically controlled trans-1,4-addition occurs.
Reduction of semibullvalene (5) with potassium more closely resembles deprotonation of tetrahydropentalenes by n-butyl-lithium-potassium t-pentoxide than it does the reduction of (5) with lithium; the former prccesses both provide the cyelo-octatetraenyl dianion (4), plausibly via the intermediate bicyclo[3.3.0]octadienediyl dianion (3).
Photoisomerisation of cyclo-octatetraene radical cations in a solid freon matrix
作者:Christopher J. Rhodes
DOI:10.1039/c39900000592
日期:——
Following γ-irradiation of cyclo-octatetraene in Freon solvents at 77 K, a single central feature was observed by ESR spectroscopy, from the parent radicalcation; after bleaching with visible light, this changed to a triplet (36.4 G) of quintets (7.8 G) pattern, assigned to the rearranged cation (IV).