In order to obtain an insight into the electronic states in connection with the condensation modes of thiophene and borepin rings, we examined 1-phenylthieno[2,3-d]borepin (2). While 1-phenylthieno[3,4-d]borepin is a peripherally conjugated compound, 2 was shown to be an aromatic compound which maintains characteristics in conjugation of individual rings.
Benzannulation of Heterocyclic Frameworks by 1,1-Carboboration Pathways
作者:René Liedtke、Fabian Tenberge、Constantin G. Daniliuc、Gerald Kehr、Gerhard Erker
DOI:10.1021/jo502753s
日期:2015.2.20
A small series of S- and N-heterocyclic 1,2-bis(trimethylsilylethynyl)arenes (2, 9, and 12) react with the strongly electrophilic borane B(C6F5)3 in consecutive 1,1-carboboration sequences to benzannulated heterocyclicsystems. With this approach, highly substituted carbazole (6), benzothiophene (10), and quinoline (14) derivatives can be synthesized. While benzannulation occurs in all three cases
Acid-Catalyzed [4+1]-Dearomatization Spiroannulation of Hydroquinones and Naphthols
作者:Zhi Li、Nan Ding
DOI:10.1055/a-2123-7565
日期:2023.12
convenient methods to access spirocyclic cyclohexadienone derivatives. The Lewis acid Bi(OTf)3 exhibited the best catalytic performance when a 1,2-dialkynylbenzene was used as the electrophile for the spiroannulation, whereas the Brønsted acid benzene-1,2-disulfonic acid was the best catalyst when 2-ethynylbenzylic esters were used as electrophiles. Most of the reaction conditions are mild, efficient, and
A convenient method for the two-step synthesis of arenediynes from 1,2-arenedialdehydes is reported. Dibromomethylenation of dialdehydes under Corey-Fuchs conditions (CBr4, Ph3P, Zn) provides the tetrabromides in excellent yields. Treatment of the tetrabromides with n-BuLi or LDA affords 3,4-unsaturated 1,5-diyiies, the key structural moiety present in several naturally occurring antitumour antibiotics, in varying yields. The key intermediates in these transformations appear to be vinylidenecarbenes or carbenoids, generated in situ via metal-halogen exchange and elimination. (c) 2005 Elsevier Ltd. All rights reserved.
The effect of thiophene ring substitution position on the properties and electrochemical behaviour of alkyne–dicobaltcarbonylthiophene complexes
A large number of Co-2(CO)(6)- and Co-2(CO)(4)(L-L)-substituted alkyne complexes (L-L = dppa and dmpm) have been prepared, characterized and studied by cyclic and square-wave voltammetry. In this paper we report a comparative electrochemical study of 2,5-, 2,4-, 3,4- and 2,3-bis(trimethylsilylethynyl) thiophene dicobalt substituted alkyne complexes, in order to evaluate the extent of the electronic interaction between the "Co2C2" redox centres depending on the position of the alkynyl substituent on the thiophene ring. (C) 2008 Elsevier B.V. All rights reserved.