197806-78-3Relevant articles and documents
Expansion of the scope of alkylboryl-bridged N → B-ladder boranes: New substituents and alternative substrates
Pammer, Frank,Schepper, Jonas,Gl?ckler, Johannes,Sun, Yu,Orthaber, Andreas
, p. 10298 - 10312 (2019)
A series of new boranes capable of forming intramolecular N → B-heterocycles has been prepared and their properties have been studied by electrochemical methods and UV-vis-spectroscopy complemented by DFT calculations. A dimethylborane (BMe2), haloborane derivatives (BBr2, BF2, BI2) and mixed cyano/isocyano-borane (B(CN)(NC)) have been prepared by different techniques. Furthermore, 2′-alkynyl-substituted 2-phenylpyridines bearing terminal tert-butyl- and trimethylsilyl-groups are introduced as a new class of substrates for hydroboration. Successful hydroboration with either 9H-borabicyclo[3.3.1]-nonane (9H-BBN), dimesitylborane (Mes2B-H), or Piers' borane ((C6F5)2B-H, BPF-H) furnished new π-extended boranes capable of forming intramolecular six- or seven-membered N → B-heterocycles (tBuBBN, SiBPF), and, in the case of Mes2BH, formation of a sterically crowded styrylborane (SiBMes2) incapable of intramolecular N → B-coordination was observed. All the boranes listed above except BMe2 have been structurally characterized, and a study of their electrochemical properties showed that the systematic variation of the substituents on boron allows for the incremental variation of the electron affinity of the phenylpyridine-model system over a total range of >0.7 eV between alkylboranes (BMe2, BBN) and B(CN)(NC). B(CN)(NC) shows the strongest N → B-bond (≈175 kJ mol-1), and highest electron-affinity observed so far, and is the first example of a borane bearing an isocyano-substituent on boron.
Synthesis of divergent benzo[b]fluorenones through cycloaromatization reactions of 1,5-enynols and 1,5-diynols
Yan, Bingyu,Fu, Yang,Zhu, Hui,Chen, Zhiyuan
, p. 4246 - 4262 (2019/03/26)
A facile and efficient synthesis of divergent benzo[b]fluorenones is described through the use of dichlorobenzoquinone-promoted oxidative cycloaromatization reactions of acyclic 1,5-enynols and 1,5-diynols. The success of these cascade reactions depends on the chemoselectivity of the initial Meyer-Schuster rearrangement to produce allenol intermediate, which is followed by regioselective Schmittel cyclization and the subsequent Friedal-Crafts alkylation or radical attack at the terminal Ar moiety. Only an oxidant and a solvent were required in the reaction, thus delivering a small library of the expected polycarbocyclic products with excellent functional group tolerance under metal-free conditions. The absorption and photoluminescence properties of the selected benzo[b] fluorenones were also investigated. The results indicated that the compound (2h) which contained an electron-donating 4-OMe group at the phenyl moiety displayed deep green color emission (491 nm).
Intramolecular anti-Phosphinoauration of Alkynes: An FLP-Motivated Approach to Stable Aurated Phosphindolium Complexes
Arndt, Sebastian,Hansmann, Max M.,Motloch, Petr,Rudolph, Matthias,Rominger, Frank,Hashmi, A. Stephen K.
supporting information, p. 2542 - 2547 (2017/03/06)
The synthesis of aurated phosphindolium complexes from easy accessible 1,5-alkynylphosphine derivatives has been studied by using gold(I) complexes featuring carbene and phosphine ligands as initiators. Upon formation of the mixed phosphine NHC/phosphine
