methyl (diethylphosphoryl)dithioformate (6) with diaryldiazomethanes 7a–d in THF at −60 °C to room temperature followed by desulfurization is shown to be a convenient method for the preparation of 2,2-disubstituted 1-(methylsulfanyl)vinyl phosphonates 8a–d. The analogous reactions with 2-diazoacenaphthen-1-one (7f) or 2-diazocamphor (7g) in refluxing THF yield selectively the corresponding (Z)- and (E)-vinyl
Diarylcarbene Complexes of Chromium from Diazo Precursors: Synthesis and Reaction with Electron-Rich Alkynes<sup>1</sup>
作者:Jürgen Pfeiffer、Karl Heinz Dötz
DOI:10.1021/om971086g
日期:1998.9.1
By reaction with pentacarbonyl(η2-cis-cyclooctene)chromium(0) (1) various diaryl diazo compounds have been converted into the corresponding chromium carbenecomplexes 9−15, 18, and 19 which, in certain cases, show extraordinary low-field 13C NMR shifts (>400 ppm) for the carbenecarbonatoms. The carbenecomplexes obtained by this “diazo route” undergo insertion of nucleophilic alkynes such as 1-(
Fluorine-Substituted Molecular Motors with a Quaternary Stereogenic Center
作者:Peter Štacko、Jos C. M. Kistemaker、Ben L. Feringa
DOI:10.1002/chem.201700581
日期:2017.5.11
A series of unprecedented second generation molecular motors featuring a quaternary stereogeniccenter substituted with a fluorine atom has been synthesized. It is demonstrated that a seemingly benign replacement of the stereogenic hydrogen for a fluorine atom, regarded as a common substituent in pharmacology, resulted in a dramatic change in the energetic profile of thermal helix inversion. The barrier
Sterically overcrowded alkenes; a stereospecific photochemical and thermal isomerization of a benzoannulated bithioxanthylidene
作者:Ben L. Feringa、Wolter F. Jager、Ben de Lange
DOI:10.1039/c39930000288
日期:——
Enantiomericallypure sterically overcrowded 12H-benzo[a]thioxanthenyl-12-(2-′methyl-9′H-thioxanthene-9′-ylidene) shows a Stereospecific photochemical and thermal isomerization, of the P-trans into the M-cis isomer (andvice versa), with a large thermal isomerization barrier (ΔG‡= 28.6 kcal mol–1)(1 cal = 4.184 J), making this type of molecule especially suitable as the key structural unit for applications
Unlocking the reactivity of diazo compounds in red light with the use of photochemical tools
作者:Katarzyna Orłowska、Klaudia Łuczak、Piotr Krajewski、João V. Santiago、Katarzyna Rybicka-Jasińska、Dorota Gryko
DOI:10.1039/d3cc05174a
日期:——
The red light-irradiation of structurally diversified diazoalkanes gives access to reactive intermediates via direct photolysis and via photosensitization or photoredox approaches.