排序方式: 共有45条查询结果,搜索用时 312 毫秒
31.
Diels-Alder cycloaddition reactions have been studied on substituted (Z)-1-benzylidene-2-methylene cyclohexanes 3. The use of very reactive dienophiles allowed the formation of the expected polycyclic structures whereas hyperbaric conditions (16 kbar) were necessary to form the adducts with less reactive dienophiles. An exo stereoselectivity was observed during the reaction with acrylates. 相似文献
32.
Shengming Ma Bukuo Ni Shaohui Lin Zhiqiang Liang 《Journal of organometallic chemistry》2005,690(23):5389-5395
Double or triple intramolecular Suzuki coupling reaction has been developed for the efficient synthesis of tri- or tetracyclic products with a benzene core in good yields. The reaction was realized via a one-pot procedure combining the hydroboration of the CC bond in the starting aryl halides and the intramolecular Suzuki coupling. 相似文献
33.
Bernd Wrackmeyer Christine Schödel Rhett Kempe Germund Glatz Awal Noor 《无机化学与普通化学杂志》2016,642(17):922-924
Complete hydroboration of cyclododecatrienes was reported to give two isomers, depending on conditions. The assignment of their structure had been attempted without unequivocal proofs. We have now used NMR spectroscopy (11B, 13C, 15N and 23Na NMR) to study the sodium amides of these two polycyclic boranes. In addition, one of the isomeric borates could be crystallized, and the X‐ray analysis revealed a cis‐,cis‐,trans configuration of the six‐membered rings reversing the original structural assignment. 相似文献
34.
Julia Ruhl Nils Oberhof Prof. Dr. Andreas Dreuw Prof. Dr. Hermann A. Wegner 《Angewandte Chemie (International ed. in English)》2023,62(15):e202300785
The incorporation of heteroatoms into hydrocarbon compounds greatly expands the chemical space of molecular materials. In this context, B−N doping takes a center stage due to its isosterism with a C=C-bond. Herein, we present a new and modular synthetic concept to access novel diazadiborabenzo[b]triphenylenes 7 a–h using the B−N doped biradical 16 as intermediate. Characterization of the photophysical properties revealed the emission spectra of the diazadibora benzo[b]triphenylenes 7 a–h can conveniently be tuned by small changes of the substitution on the boron-atom. All of the diazadibora compounds show a short life-time phosphorescence. Additionally, we were able to rationalize the excited-state relaxation of the diazadiboraacene 7 a via intersystem crossing by quantum chemical calculations. The new synthetic strategy provides an elegant route to various novel B−N doped acenes with great potential for applications in molecular materials. 相似文献
35.
Dongfang Meng Samuel J. Danishefsky 《Angewandte Chemie (International ed. in English)》1999,38(10):1485-1488
A reaction sequence made up of a Sakurai reaction, ketene cyclization, sulfur-directed Baeyer–Villiger reaction, and tandem lactone cleavage/isomerization provided the fully functionalized core of the CP compounds. Key steps were the methanolysis of 1 , which leads via 2 to the CP precursor 3 . 相似文献
36.
37.
Hans Bock Zdenek Havlas Katayoun Gharagozloo-Hubmann Mark Sievert 《Angewandte Chemie (International ed. in English)》1999,38(15):2240-2243
Partly solvent-separated and partly solvent-shared , the contact ion triple of the 9,10-diphenyltetrabenz[a,c,h,j]anthracene dianion is formed by the ultrasonically activated reaction of hexaphenylbenzene with lithium metal powder in 1,2-dimethoxyethane (dme) [Eq. (1)]. The proposed microscopic pathway for this reaction—twofold dehydrogenation and C−C bond formation—is supported by quantum-chemical calculations. 相似文献
38.
Valeriya G. Melekhina Vitaly S. Mityanov Boris V. Lichitsky Andrey N. Komogortsev Artem N. Fakhrutdinov Elena D. Daeva Michail M. Krayushkin 《Tetrahedron letters》2019,60(26):1745-1747
Ultraviolet irradiation of hydroxyl substituted terarylenes provided a simple, efficient, and environmentally friendly method for the synthesis of imidazo[1,2-a]pyridines. The starting terarylenes were prepared via the one-pot, three-component condensation of readily accessible arylglyoxals, 2-aminopyridines, and dimedone. 相似文献
39.
Vivekanantan S. Iyer Kimihiro Yoshimura Volker Enkelmann Rebekka Epsch Jürgen P. Rabe Klaus Müllen 《Angewandte Chemie (International ed. in English)》1998,37(19):2696-2699
At the limits of analytical investigation one finds the nanodimensional C60 graphite segment 1 , which, thanks to its long-chain alkyl substituents, is soluble. Monolayers of 1 on graphite can be characterized by scanning tunneling microscopy. 相似文献
40.
Ulrike Rohr Peter Schlichting Arno Bhm Markus Gross Klaus Meerholz Christoph Bruchle Klaus Müllen 《Angewandte Chemie (International ed. in English)》1998,37(10):1434-1437
Tempering of polystyrene films containing the novel liquid crystalline coronenebis(dicarboximide)s 2 , which are formed by an easy route from perylene-3,4;9,10-tetracarboxylic dianhydride ( 1 ), leads to a shift of the emission within a few seconds. This could be used for dot-by-dot coloring and thus optical displays. The photoluminescence properties of 2 in the solid matrix are dependent on the nature of the aggregates formed. 相似文献