Transition metal complexes in organic synthesis.: Part 47.: Organic synthesis via tricarbonyl(η4-diene)iron complexes

The protection of conjugated dienes by coordination to the tricarbonyliron fragment offers many potential applications of the resulting complexes to organic synthesis. The preparation of tricarbonyl(eta(4)-1,3-diene)iron complexes is readily achieved by a 1-azabutadiene-catalyzed complexation of the free ligands, An asymmetric catalytic complexation of prochiral cyclohexa-1,3-dienes with pentacarbonyliron using chiral 1-azabutadienes affords chiral nonracemic complexes, The chiral tricarbonyliron complexes of acyclic butadienes represent versatile starting materials for the synthesis of a broad range of polyunsaturated natural products. Consecutive carbon-carbon and carbon-nitrogen bond formations of the tricarbonyliron-cyclohexa-1,3-diene complexes and arylamines provide many biologically active carbazole alkaloids and a tetracyclic subunit of the discorhabdin alkaloids, The iron-mediated [2+2+1] cycloaddition of trimethylsilylacetylenes and carbon monoxide affords stable 2,5-bis(trimethylsilyl)-substituted cyclopentadienones which are useful substrates for further cycloadditions.