Some chemistry of orthomanganated ketones
type: CreativeWork
description: The major part of this thesis describes the preparation and reactions of orthomanganated aromatic ketones, such as (1), diagram. Among the new species characterised are substituted acetophenones, analogues of (1), namely: 3,4,5-trimethoxy (3); 4,5,6-trimethoxy (4); 3-t-butyldimethylsiloxy-4,5-dimethoxy (5); 4,5-dimethoxy (6); 5,6-dimethoxy (7); 3-benzyloxy-4,5-dimethoxy (8); and 3-t-butyldimethylsiloxy (9). Hetero aromatic ketones have been used to prepare the corresponding orthomanganated compounds (10), (11), (12), (14) and (15) from the respective ketones 2-acetylthiophene, 3-acetyl-2,5-dimethylthiophene, 2-acetyl-N-methylpyrrole, 3-acetylindole and 2- acetylfuran. The crystal structure of η²-(3-acetyl-2,5-dimethylthien-4-yl)tetracarbonylmanganese (11) has been determined. The 5-manganated derivative (13) of flavanone has also been made. Attempted orthometallations of acetophenones with C₆H₅CH₂Co(CO)₄, C₆H₅CH₂Fe(CO)₂Cp and Pd(OAc)₂ were unsuccessful. Reaction of (4) with Br₂ in carbon tetrachloride gave the orthobromoacetophenone 2'-bromo-3' ,4' ,5'-trimethoxyacetophenone (21) plus [Mn(CO)₄Br]₂. The corresponding orthoiodoacetophenone (28) and [Mn(CO)₄Cl]₂ was obtained using ICl. Other orthohalogenated ketones were obtained similarly. The reactions were sometimes unsuccessful (e.g. for (1)) or complicated (e.g. (5) competitive ring bromination). Oxidation of (1) or (4) with cerium (IV) ammonium nitrate (0.5 mol) in CD₃CO₂D gives the corresponding orthomonodeuterio acetophenones (19) or (20). A by-product from the oxidation of (4), the cyclic hemiketal, (36), was identified by X-ray crystal structure analysis, and one other product, the lactone, (37) was identified spectrally. Determination by ¹H-NMR of the ratio of the 3-deuterio- (1a) to 3-protio- (1) formed in the orthometallation of orthomonodeuterio acetophenone (19) by C₆H₅CH₂Mn(CO)₅ gave a hydrogen isotope effect of 3.6. Similarly, for 2'-deuterio-3' ,4' ,5'-trimethoxyacetophenone (20) the value was 2.9. Ho…
abstract: The major part of this thesis describes the preparation and reactions of orthomanganated aromatic ketones, such as (1), diagram. Among the new species characterised are substituted acetophenones, analogues of (1), namely: 3,4,5-trimethoxy (3); 4,5,6-trimethoxy (4); 3-t-butyldimethylsiloxy-4,5-dimethoxy (5); 4,5-dimethoxy (6); 5,6-dimethoxy (7); 3-benzyloxy-4,5-dimethoxy (8); and 3-t-butyldimethylsiloxy (9). Hetero aromatic ketones have been used to prepare the corresponding orthomanganated compounds (10), (11), (12), (14) and (15) from the respective ketones 2-acetylthiophene, 3-acetyl-2,5-dimethylthiophene, 2-acetyl-N-methylpyrrole, 3-acetylindole and 2- acetylfuran. The crystal structure of η²-(3-acetyl-2,5-dimethylthien-4-yl)tetracarbonylmanganese (11) has been determined. The 5-manganated derivative (13) of flavanone has also been made. Attempted orthometallations of acetophenones with C₆H₅CH₂Co(CO)₄, C₆H₅CH₂Fe(CO)₂Cp and Pd(OAc)₂ were unsuccessful. Reaction of (4) with Br₂ in carbon tetrachloride gave the orthobromoacetophenone 2'-bromo-3' ,4' ,5'-trimethoxyacetophenone (21) plus [Mn(CO)₄Br]₂. The corresponding orthoiodoacetophenone (28) and [Mn(CO)₄Cl]₂ was obtained using ICl. Other orthohalogenated ketones were obtained similarly. The reactions were sometimes unsuccessful (e.g. for (1)) or complicated (e.g. (5) competitive ring bromination). Oxidation of (1) or (4) with cerium (IV) ammonium nitrate (0.5 mol) in CD₃CO₂D gives the corresponding orthomonodeuterio acetophenones (19) or (20). A by-product from the oxidation of (4), the cyclic hemiketal, (36), was identified by X-ray crystal structure analysis, and one other product, the lactone, (37) was identified spectrally. Determination by ¹H-NMR of the ratio of the 3-deuterio- (1a) to 3-protio- (1) formed in the orthometallation of orthomonodeuterio acetophenone (19) by C₆H₅CH₂Mn(CO)₅ gave a hydrogen isotope effect of 3.6. Similarly, for 2'-deuterio-3' ,4' ,5'-trimethoxyacetophenone (20) the value was 2.9. Ho…
author: Gommans, Louis H. P.
license: https://researchcommons.waikato.ac.nz/bitstreams/bbbc2d88-f925-40d8-95df-f7c7c62796e1/download
date published: 1986
date modified: 2026-07-24T05:57:27Z
provider: University Waikato
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: The University of Waikato