AbstractThe conditions for the novel tandem Pauson‐Khand reaction have been explored. The highly functionalized tetracyclic compounds 11c, 11d, and 16 were prepared from the ene‐diynes 4c, 4d, and 10 by treatment with 2 equiv. of [Co2(CO)8] and 4‐methylmorpholine N‐oxide (NMO) or Me3NO in yields of 24, 22, and 53%, respectively (Table). In the presence of 1–3 equiv. of H2O added to the NMO used for induction of the Pauson‐Khand reaction of 6d, a mixture of cyclopentanones 17/18 and cyclopentenones 12/13 was obtained (Scheme 5). The first example of a [Co2(CO)6]‐induced highly stereoselective ene reaction is described. To account for these results, the formation of intermediates are proposed (Schemes 6 and 7) which hitherto have not been considered in the mechanistic description of the Pauson‐Khand reaction.
作者:Marc Thommen、Andrei L. Veretenov、R�gine Guidetti-Grept、Reinhart Keese
DOI:10.1002/hlca.19960790214
日期:1996.3.20
AbstractThe conditions for the novel tandem Pauson‐Khand reaction have been explored. The highly functionalized tetracyclic compounds 11c, 11d, and 16 were prepared from the ene‐diynes 4c, 4d, and 10 by treatment with 2 equiv. of [Co2(CO)8] and 4‐methylmorpholine N‐oxide (NMO) or Me3NO in yields of 24, 22, and 53%, respectively (Table). In the presence of 1–3 equiv. of H2O added to the NMO used for induction of the Pauson‐Khand reaction of 6d, a mixture of cyclopentanones 17/18 and cyclopentenones 12/13 was obtained (Scheme 5). The first example of a [Co2(CO)6]‐induced highly stereoselective ene reaction is described. To account for these results, the formation of intermediates are proposed (Schemes 6 and 7) which hitherto have not been considered in the mechanistic description of the Pauson‐Khand reaction.
Fenestranes in Recent Synthetic Developments
作者:M. Thommen、Reinhart Keese
DOI:10.1055/s-1997-755
日期:1997.3
The systematic description of planarizing distortions of tetracoordinate carbon is outlined and specifically discussed for C(C)4 moieties which form the central part of fenestranes. Recent synthetic developments of the preparation of stereoisomeric [4.5.5.5]fenestranes and [5.5.5.5]fenestranes are described. Transformations with the aim of increased planarizing distortions are presented. The interaction of Fe2(CO)9 with a fenestradiene led to three structurally well defined Fe-carbonyl complexes.