Characterization and Fate of a Septanosyl Ferrier Cation in the Gas and Solution Phases

Journal article

Ferrier reactions follow a mechanistic pathway whereby Lewis acid activation of a cyclic enol ether facilitates departure of an allylic leaving group to form a glycosyl Ferrier cation. Attack on the Ferrier cation provides a new acetal linkage concurrent with the transposition of the alkene moiety. The idiosyncratic outcomes of Ferrier reactions of seven-membered ring carbohydrate-based oxepines prompted an investigation of its corresponding septanosyl Ferrier cation. Experiments that characterized the ion, including gas-phase cryogenic IR spectroscopy matched with density functional theory-calculated spectra of candidate cation structures, as well as product analysis from solution-phase Ferrier reactions, are reported here. Results from both approaches revealed an inclination of the seven-membered ring cation to contract to five-membered ring structures. Gas-phase IR spectra matched best to calculated spectra of structures in which five-membered dioxolenium formation opened the oxepine ring. In the solution phase, an attack on the ion by water led to an acyclic enal that cyclized to a C-methylene-aldehydo arabinofuranoside species. Attack by allyl trimethylsilane, on the other hand, was diastereoselective and yielded a C-allyl septanoside

Authors: Greis, K; Griesbach, CE; Kirschbaum, C; Meijer, G; von Helden, G

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: American Chemical Society
• Journal: The Journal of Organic Chemistry
• Volume: 88
• Issue: 9
• Pages: 5543-5553
• Publication date: 2023-04-24
• DOI: 10.1021/acs.joc.3c00079
• EISSN: 1520-6904
• ISSN: 0022-3263
• Language: English
• Keywords: Alkene; Chemistry; Mass spectrum; Methylene; Catalysis; Ring (chemistry); Organic chemistry; Ion; Enol; Moiety; Lewis acids and bases; Stereochemistry; Allylic rearrangement; Acetal