Conformational analysis of tricarbonyl(diene) iron compounds

Highly Stereoselective Total Synthesis of Multiply Protected 3-Amino-3,6-dideoxyaldohexoses (Mycosamine/Mycaminose) by Aldol Condensation Reaction, Mediated by Tin Triflate, of Tricarbonyliron/α-Aminodienone Complexes

“…[23] Even with tetramethylammonium triacetoxyhydridoborate, known for converting β-hydroxy ketones into anti-1,3-diols, [24] we obtained nearly the same quantities of both isomers [39% ψ-endo-alcohol (Ϫ)-9; 35% ψ-exo-alcohol (Ϫ)-10] when the reaction was carried out in acetonitrile/acetic acid at Ϫ20°C. When it was carried out at room temperature, the yield of ψ-exo-alcohol (Ϫ)-10 could be increased to 67%, but the ψ-endo-alcohol was still present.…”

Stoichiometric Applications of Acyclic π-Organoiron Complexes to Organic Synthesis

“…that these exist predominantly as one conformer [38]. Since X-ray crystal structures of complexes 30 generally exhibit the s-cis geometry, then this conformer is also proposed to be the predominant species in solution.…”

“…This analysis is consistent with the experimental results. Reduction of (E,Edienone)Fe(CO) 3 complexes 30 proceeds with high diastereoselectivity (>90% de) to afford predominantly the ψ-endo alcohol [38]. In comparison, nucleophilic addition to (2E,4-dienal)Fe(CO) 3 complexes (31) proceeds with variable diastereoselectivity, depending on both the complex and the nucleophile (Scheme 6) [39].…”

Tricarbonyliron complexes: an approach to acyclic stereocontrol

“…The reduction of dienone tricarbonyliron complexes by NaBH 4 has long since been shown to be highly diastereoselective. 9 Franck-Neumann et al have further shown that 1-keto h 4 -diene complexes 8 react with complete stereocontrol with organolithium reagents affording a single diastereoisomeric product 9. The stereoselectivity is readily accounted for by the proposed model with addition of the nucleophile proceeding onto the s-cis-conformation of the ketone anti to the bulky Fe(CO) 3 group (Scheme 1).…”

“…Upon complexation to Fe(CO) 3 , however, a single CNO stretching frequency is observed suggesting that only one conformer is significantly populated. 9 The preference of ketone-functionalised dienetricarbonyliron complexes to adopt a single conformation is widely accepted and both NOE and X-ray data support the exclusive adoption of an s-cis conformation. Similarly, p-allyltricarbonyliron lactone complexes bearing ketone functionality in the side-chain of the allyl ligand adopt exclusively an s-cis conformation in both the solid state (as determined by X-ray structure analysis) (Fig.…”