Zwei fÄlle von angeborenem mangel der patella

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Intramolecular cooperativity in frustrated Lewis pairs

Körte LA, Blomeyer S, Heidemeyer S, Mix A, Neumann B, Mitzel NW. Intramolecular cooperativity in frustrated Lewis pairs. CHEMICAL COMMUNICATIONS. 2016;52(64):9949-9952.The doubly Lewis-acid functionalised aniline PhN[(CH2)(3)B(C6F5)(2)](2) features two competing boron functions in fast exchange for binding to the central Lewis base. It shows catalytic activity typical for FLPs in H/D-scrambling and catalytic hydrogenation experiments. By contrast, the singly acid-functionalised PhMeN(CH2)(3)B(C6F5)(2) reveals a dramatically smaller catalytic activity in analogous experiments

Intramolecular pyridine-based frustrated Lewis-pairs

Körte LA, Warner R, Vishnevskiy Y, Neumann B, Stammler H-G, Mitzel NW. Intramolecular pyridine-based frustrated Lewis-pairs. Dalton Transactions. 2015;44(21):9992-10002.Deprotonation of the methylpyridines 2,6-lutidine, 2-picoline, 4-dimethylamino-2,6-dimethylpyridine as well as 2,6-dimethyl-4-(piperidine-1-yl) pyridine with n-butyllithium or n-butyllithium/KO-t-Bu at the methyl positions led to the corresponding organolithium or -potassium compounds. Treatment with ClB(C6F5)(2) resulted in formation of the 2-borylmethylpyridines py-CH2-B(C6F5)(2). They are monomeric and form intramolecular B-N bonds and four-membered rings. A short intramolecular B-N distance was observed in the crystal structure of the dimethylamino-functionalized derivative and proposed to be responsible for the low reactivity of the products towards hydrogen, thf, acetonitrile and CO2. Hydroboration of 6-tert-butyl-2-but-4'-enylpyridine with HB(C6F5)(2) led to the corresponding hydroboration product t-Bu-py-(CH2)(4)-(C6F5)(2) which shows no intramolecular B-N bond formation due to steric crowding. H/D-scrambling experiments with a H-2/D-2 mixture revealed its reactivity towards hydrogen

Improved Access to 1,8-Dichloro-10-(ethynyl)anthracene: A Useful Building Block for (Semi-)rigid Organic Frameworks

Lamm J-H, Niermeier P, Körte LA, Neumann B, Stammler H-G, Mitzel NW. Improved Access to 1,8-Dichloro-10-(ethynyl)anthracene: A Useful Building Block for (Semi-)rigid Organic Frameworks. SYNTHESIS-STUTTGART. 2018;50(10):2009-2018.An easy access to 1,8-dichloro-10-(ethynyl)anthracene is reported, which is widely applicable for building up rigid linkers between two 1,8-dichloroanthracene units. For this, 1,8-dichloroanthren-10(9 H )-one was reacted with ethynylmagnesium bromide in the presence of CeCl (3) ; the yield was 65%. This building block was used as a substrate in (cross-)coupling reactions and some examples of linked 1,8-dichloroanthracen-10-yls (e.g., 1,8-bis[(1,8-dichloroanthracen-10-yl)-ethynyl]naphthalene or 1,2-bis[(1,8-dichloroanthracen-10-yl)ethynyl]-benzene) were synthesized in good to moderate yields. Linked 1,8-dichloroanthracen-10-yl derivatives were also synthesized by cross-coupling reactions using 10-bromo-1,8-dichloroanthracene and doubly ethynyl-substituted substrates. Linkers between the 1,8-dichloroanthracene units were: butadiynediyl, dimethylsilyldiethynyl, octa-1,7-diyne-1,8-diyl, propane-1,3-diylbis(dimethylsilyl)diethynyl, benzene-1,2-diethynyl, naphthalene-1,8-diyldiethynyl, and anthracene-1,8-diyldiethynyl. The new anthracene compounds were characterized by NMR spectroscopy, high-resolution mass spectrometry, and, in part, by X-ray diffraction experiments