Asymmetric synthesis via iron acyl complexes

Thesis

This thesis describes the applications to asymmetric synthesis of the highly diastereoselective carbon-carbon bond forming reactions of α,β-unsaturated acyl ligands bound to the chiral iron auxiliary [(η⁵-C₅H₅)Fe(CO)(PPh₃)].

Chapter 1 briefly reviews the use of chiral auxiliaries in asymmetric synthesis.

Chapter 2 discusses the conformation of [(η⁵-C₅H₅)Fe(CO)(PPh₃)COCH₃] with reference to its X-ray crystal structure. A method for determining the absolute configuration of (+)- and (-)-[(η⁵-C₅H₅)Fe(CO)(PPh₃)COCH₃] is described as well as methods for determining their optical purities.

Chapter 3 describes methods for the preparation of α,β-unsaturated acyl complexes. The Peterson reaction between the enolate derived from [(η⁵-C₅H₅)Fe(CO)(PPh₃) COCH₂ Si (CH₃)₃] and aldehydes gives complexes of the type [(η⁵-C₅H₅)Fe(CO)(PPh₃) COCH=CHR] as mixtures of E and Z isomers. Sodium hydride-induced elimination of methanol from either diastereoisomer of the corresponding β-methoxy acyl complex gives the E isomer stereo-selectively. Complexes of the type [η⁵-C₅H₅)Fe(CO)(PPh₃)COC(R)=CH₂] are similarly prepared from the corresponding β-methoxy acyl complexes. The conformations of E- and Z- [η⁵-C₅H₅)Fe(CO)(PPh₃)COC(R)=CH₂] are discussed with reference to the X-ray crystal structures of the β-methoxy substituted complexes.

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Authors: Walker, J; Walker, Jonathan

• Publication date: 1986
• Type of award: DPhil
• Level of award: Doctoral
• Awarding institution: University of Oxford
• Language: English
• Subjects: Asymmetric synthesis; Iron compounds; Stereochemistry; Acyl halides; Chirality