FENESTRANES IN RECENT SYNTHETIC DEVELOPMENTS

The systematic description of planarizing distortions of tetracoordina te carbon is outlined and specifically discussed for C(C)(4) moieties which form the central part of fenestranes. Recent synthetic developme nts of the preparation of stereoisomeric [4.5.5.5]fenestranes and [5.5 .5.5]fenestranes are described. Transformations with the aim of increa sed planarizing distortions are presented. The interaction of Fe-2(CO) (9) with a fenestradiene led to three structurally well defined Fe-car bonyl complexes.