Modes of Reactivity of Cyclic Diynes: Probing the
<i>syn</i>
/
<i>anti</i>
Selectivity of Tetrathiacycloalkadiynes and Mono(alkyne)cobalt Complexes
作者:Christoph Benisch、Daniel B. Werz、Rolf Gleiter、Frank Rominger、Thomas Oeser
DOI:10.1002/ejic.200390141
日期:2003.3
analogues (8b−8e) in order to probe the reactivity of electron-rich cyclic diynes. Both mono- [B(m.n)] and bis(cyclobutadiene) [C(m.n)] complexes were isolated as products of these reactions and the anti/syn ratio of C(m.n) was determined. For m, n < 4 the syn isomers dominate and this is attributed to the configuration of the intermediate metallacycle which is correlated with the conformations of the
Structural Properties of Bis(hexacarbonyldicobalt) Complexes with Heteroatoms Next to the Former Triple Bonds − A Contribution to the Mechanism of the Pauson−Khand Reaction
作者:Daniel B. Werz、J. Hilko Schulte、Bernhard J. Rausch、Rolf Gleiter、Frank Rominger
DOI:10.1002/ejic.200300862
日期:2004.6
The bis(hexacarbonyldicobalt) complexes of cyclic diynes with sila-, thia- and selena-substituted acetylene units have been isolated. The structural features of these complexes have been elucidated by means of X-ray diffraction analyses on single crystals. In three cases (24′, 25′ and 29′) the X-ray investigations show bis(pentacarbonyldicobalt) complexes instead of bis(hexacarbonyldicobalt) ones.
The four-component cyclization of dilithium acetylide with dithiocyanatoalkanes yielded the hitherto unknown tetrathiacyclodiynes 34, 38, 41, and 43 in moderate yields. The use of the trimethylsilyl protecting group allowed a more efficient and flexible stepwise approach with good yields. The resulting tetrathiacyclodiynes 25−44 were investigated by X-ray analysis. For ring systems with a twist-chair