Tayama E, Kawai K. Synthesis of tertiary alkyl fluorides and chlorides by site-selective nucleophilic ring-opening reaction of α-aryl azetidinium salts.
RSC Adv 2021;
11:39607-39618. [PMID:
35492462 PMCID:
PMC9044468 DOI:
10.1039/d1ra08706a]
[Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Accepted: 12/03/2021] [Indexed: 12/24/2022] Open
Abstract
Site-selective nucleophilic ring-opening reactions of 2-arylazetidine-2-carboxylic acid ester-derived tetraalkyl ammonium salts 2 with tetrabutylammonium halides (Bu4NX) to give tertiary alkyl halides are successfully demonstrated. For example, a nucleophilic ring-opening reaction of 2-(o-tolyl) derivative 2a with 1.2 equivalents of tetrabutylammonium fluoride (Bu4NF) in THF at 60 °C preferentially proceeded at a more substituted carbon atom (2-position) compared to a less-substituted carbon atom (4-position) and afforded tert-butyl 4-(dimethylamino)-2-fluoro-2-(o-tolyl)butanoate 3aa in 71% yield as the corresponding tertiary alkyl fluoride. This result was applied to synthesize optically active organofluorine compounds starting from commercially available (R)-1-phenylethylamine.
Site-selective nucleophilic ring-opening of 2 with Bu4NX proceeded at a much-substituted 2-position preferentially and produced tertiary alkyl halides 3.![]()
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