Synthesis and catalytic evaluation of chiral ferrocenyl p^p and p^n palladium(II) complexes
type: CreativeWork
description: Chapter 2 outlines initial attempts made to synthesize analogues of the P,N-type chiral ligands (η5-C5H5)Fe(η5-C5H3-PPh2)C*H(OH)(3,5-R2pz) R = H SPNa and R = Me SPNb first prepared by Togni, and the P,P-type chiral ligands (η5-C5H5)Fe(η5-C5H3-PR2)C*H(OH)(PPh2) R = Ph SPPa, R = i-Pr SPPb of the Josiphos family. In these ligands, the methyl group on the stereogenic carbon is replaced with a hydroxyl group. The preparation of SPNa and SPNb included the use of the scaffolds (η5-C5H5)Fe(η5-C5H4)(CO)(3,5-R2pz) R = H 3a and R = Me 3b which were prepared from the reaction of ferrocenoyl chloride with appropriate pyrazolyl moieties. It was unfortunately discovered that neither 3a nor 3b could be reduced to the corresponding alcohol derivatives (η5-C5H5)Fe(η5-C5H4C*H(OH)(3,5-R2pz) R = H 3-OHa and R = Me 3-OHb which were the required intermediates towards the preparation of SPNa and SPNb. The preparation of SPPa and SPPb used the scaffold (η5-C5H5)Fe(η5-C5H4)(CO)(PPh2) 4 which was prepared similarly to ligands 3a and 3b using lithium diphenylphosphine. Disappointingly, scaffold 4 was obtained in yields less than 10%. Furthermore, it could also not be reduced to the required intermediate (η5-C5H5)Fe(η5-C5H4)C*H(OH)(PPh2) 4-OH as it was the case for 3a and 3b. The alternative scaffolds (η5-C5H5)Fe(η5-C5H4-COMe) 5 and (η5-C5H5)Fe(η5-C5H4-PPh2) 7 were then synthesized. Compound 5 could be reduced to (η5-C5H5)Fe(η5-C5H4) C*H(OH)(Me) 5-OH which was subsequently used to prepare the ligand intermediates (η5-C5H5)Fe(η5-C5H4)C*H(3,5-R2pz)(Me) where R = H 6a and R = Me 6b by a substitution reaction with appropriate pyrazolyl moieties. The lithiatiation of 6b followed by the reaction with chlorodiphenylphosphine yielded the chiral ligand (η5-C5H5)Fe(η5-C5H3-PPh2)C*H(3,5-Me2pz)(Me) LPNb. Friedel-Crafts acetylation of 7 with acetyl chloride afforded a heteroannular intermediate (η5-C5H4-PPh2)Fe(η5-C5H4-COMe) 8 instead of the desired homoannular intermediate. This intermediate could be reduc…
abstract: Chapter 2 outlines initial attempts made to synthesize analogues of the P,N-type chiral ligands (η5-C5H5)Fe(η5-C5H3-PPh2)C*H(OH)(3,5-R2pz) R = H SPNa and R = Me SPNb first prepared by Togni, and the P,P-type chiral ligands (η5-C5H5)Fe(η5-C5H3-PR2)C*H(OH)(PPh2) R = Ph SPPa, R = i-Pr SPPb of the Josiphos family. In these ligands, the methyl group on the stereogenic carbon is replaced with a hydroxyl group. The preparation of SPNa and SPNb included the use of the scaffolds (η5-C5H5)Fe(η5-C5H4)(CO)(3,5-R2pz) R = H 3a and R = Me 3b which were prepared from the reaction of ferrocenoyl chloride with appropriate pyrazolyl moieties. It was unfortunately discovered that neither 3a nor 3b could be reduced to the corresponding alcohol derivatives (η5-C5H5)Fe(η5-C5H4C*H(OH)(3,5-R2pz) R = H 3-OHa and R = Me 3-OHb which were the required intermediates towards the preparation of SPNa and SPNb. The preparation of SPPa and SPPb used the scaffold (η5-C5H5)Fe(η5-C5H4)(CO)(PPh2) 4 which was prepared similarly to ligands 3a and 3b using lithium diphenylphosphine. Disappointingly, scaffold 4 was obtained in yields less than 10%. Furthermore, it could also not be reduced to the required intermediate (η5-C5H5)Fe(η5-C5H4)C*H(OH)(PPh2) 4-OH as it was the case for 3a and 3b. The alternative scaffolds (η5-C5H5)Fe(η5-C5H4-COMe) 5 and (η5-C5H5)Fe(η5-C5H4-PPh2) 7 were then synthesized. Compound 5 could be reduced to (η5-C5H5)Fe(η5-C5H4) C*H(OH)(Me) 5-OH which was subsequently used to prepare the ligand intermediates (η5-C5H5)Fe(η5-C5H4)C*H(3,5-R2pz)(Me) where R = H 6a and R = Me 6b by a substitution reaction with appropriate pyrazolyl moieties. The lithiatiation of 6b followed by the reaction with chlorodiphenylphosphine yielded the chiral ligand (η5-C5H5)Fe(η5-C5H3-PPh2)C*H(3,5-Me2pz)(Me) LPNb. Friedel-Crafts acetylation of 7 with acetyl chloride afforded a heteroannular intermediate (η5-C5H4-PPh2)Fe(η5-C5H4-COMe) 8 instead of the desired homoannular intermediate. This intermediate could be reduc…
author: Masikane, Siphamandla Cecil
keywords: chiral ferrocenyl --palladium (II) --complexes
license: https://devspace.unizulu.ac.za/bitstreams/5bbb4c19-aac3-48e6-b635-379a3806942c/download
date published: 2013
date modified: 2026-07-24T06:17:03Z
provider: University of Zululand
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of Zululand