Synthesis of N-alkylated 4-fluoro-5-phenylpyrrole-2-carboxylate via isolable pyrroline ionic intermediatesopen access
- Authors
- Kim, Sung Kwan; Jun, Changsoo; Kwak, Kyungchell; Park, Kwangyong; Chai, Kyuyun
- Issue Date
- Dec-2007
- Publisher
- KOREAN CHEMICAL SOC
- Keywords
- beta-fluoropyrrole; pyrrole derivatives; anionic pathway
- Citation
- BULLETIN OF THE KOREAN CHEMICAL SOCIETY, v.28, no.12, pp 2324 - 2328
- Pages
- 5
- Journal Title
- BULLETIN OF THE KOREAN CHEMICAL SOCIETY
- Volume
- 28
- Number
- 12
- Start Page
- 2324
- End Page
- 2328
- URI
- https://scholarworks.bwise.kr/cau/handle/2019.sw.cau/23883
- DOI
- 10.5012/bkcs.2007.28.12.2324
- ISSN
- 0253-2964
1229-5949
- Abstract
- Organic fluorine chemistry produces many useful products. This paper elucidates the reaction of ethyl-4,4-difluoro-2-iodo-5-oxo-5-phenylpentanoate (2) with primary amines in a one-pot scheme. The reaction produced a series of beta-fluoropyrrole derivatives at ambient temperatures. In this reaction, the less bulky the primary amine the higher was the resultant yield. When (2) and aqueous methylamine (40%) were allowed to react below 0 degrees C, 5-(ethoxycarboxyl)-1-methyl-3,3-difluoro-2-hydroxy-2-phenylpyrrolidine, an intermediate molecule for 2-ethyl-4-flouro-1-methyl-5-phenylpyrrole-2-carboxylate (5), was isolated first. Then, (5) reacted with hydroperchloric acid and acetic anhydride to form 5-(ethoxycarboxyl)-1-methyl-3,3-difluoro-2-phenylpyrrolinium perchlorate (6), which was converted to 2-ethyl-4-flouro-1-methyl-5-phenylpyrrole-2-carboxylate gradually in the presence of a base. Our experiments demonstrate that the formation of 2-ethyl-4flouro-l-methyl-5-phenylpyrrole-2-carboxylate occurs via both one-pot schemes and stepwise pathways, depending on the reaction conditions. The isolation and characterization of the isolated intermediate (6) suggest an anionic pathway for this reaction.
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