A two-phase bromination process using tetraalkylammonium hydroxide for the practical synthesis of α-bromolactones from lactones

• Yuki Yamamoto,
• Akihiro Tabuchi,
• Kazumi Hosono,
• Takanori Ochi,
• Kento Yamazaki,
• Shintaro Kodama,
• Akihiro Nomoto and
• Akiya Ogawa

Beilstein J. Org. Chem. 2021, 17, 2906–2914, doi:10.3762/bjoc.17.198

• facilitate the industrial use of α-bromolactones as important intermediates. Keywords: α-bromolactone; metal-free; one-pot operation; tetraalkylammonium hydroxide; two-phase system; Introduction Lactones are important heterocycles in the organic chemistry, materials science, and medicinal chemistry fields

• , and bromolactones are important synthetic intermediates for selectively, effectively, and practically introducing lactone units into organic molecules [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]. Among brominated lactones, the α-bromolactone, in which the bromine atom is located at

• based on this bromination protocol. After ring-closing 2a, the generated α-bromolactone 3a was extracted into the organic layer, whereas the formed n-Bu4N+Br− dissolved in both the aqueous and organic layers. N-Bu4N+Nu− is formed when Na+Nu− (Nu−: nucleophile) is added to the reaction mixture, which is