Neue selenreiche 1,3-Dichalkogenol-2-selone via 4,5-Dilithio-1,3-dichalkogenol-2-selone
作者:Helmut Poleschner、Reiner Radeglia、Joachim Fuchs
DOI:10.1016/0022-328x(92)83086-w
日期:1992.4
1,3-Dithiole-2-thione (1), 1,3-diselenole-2-selone (2), 1,3-thiaselenole-2-thione (3), 1,3-dithiole-2-selone (4), 1,3-diselenole-2-thione (5) and 1,3-thiaselenole-2-selone (6) are dilithiated with lithium diisopropyl amide in the 4/5 position, followed by selenation (thiolation) and complexation of the resulting heterocyclic diselenolates (dithiolates) to the zinc bis-chelates (tetrabutylammonium or tetraphenylphosphonium salts).These zinc complexes react with benzoyl chloride to the corresponding selenole and thiole esters. It is noteworthy that the heterocyclic thiones with one or two ring selenium atoms undergo ring transformation (Dimroth rearrangement) during the lithiation chalcogenation sequence, whilst the thione sulfur and one ring selenium atom change their places: 3 --> 1,3-dithiole-2-selone-4,5-diselenolate or dithiolate structure, 5 --> 1,3-thiaselenole-2-selone-4,5-diselenolate structure. This observed rearrangement is verified by independent synthetic pathways. The corresponding identical zinc chelates 12 and complex 18 result from the precursors 3 and 4, and 5 and 6, respectively. Trapping experiments support the conclusion that this rearrangement takes place already during lithiation. The zinc chelates and thiole and selenole esters are characterized in detail by IR and above all by C-13 and Se-77 NMR spectroscopy, including NMR shift values of the precursor heterocycles. The X-ray crystal structure determination of bis(tetraphenylphosphonium)-bis(1,3-thiaselenole-2-selone-4,5-diselenolato) zincate (18), obtained from 5, shows the rearrangement of 5 to the 1,3-thiaselenole-2-selone partial structure in 18.