Cs₂CO₃-Promoted reaction of tertiary bromopropargylic alcohols and phenols in DMF: a novel approach to α-phenoxyketones

• Ol'ga G. Volostnykh,
• Olesya A. Shemyakina,
• Anton V. Stepanov and
• Igor' A. Ushakov

Beilstein J. Org. Chem. 2022, 18, 420–428, doi:10.3762/bjoc.18.44

• bromopropargylic alcohols and Cs2CO3. Keywords: acetylenic alcohol; bromoacetylene; 1,3-dioxolan-2-one; phenols; phenoxyketone; Introduction Due to the relative stability, ease of handling and the presence of reactive sites, bromoacetylenes are widely applied in synthetic organic chemistry. They are known to be

• 5% preparative yield (Table 1, entry 4), whereas the use of 2 equiv of Cs2CO3 led to slightly more selective reaction (Table 1, entry 5). Further lowering the temperature reduces the selectivity toward phenoxyketone 4a. At room temperature, the full conversion of bromopropargylic alcohol 1a took 15

• in 6–9% preparative yield. Hydrocarbonates CsHCO3 and KHCO3 were also tested in the reaction, which gave 5-bromomethylene-1,3-dioxolan-2-one 6a as a major product in 29–36% yield (Table 1, entries 11 and 12). Considering that hydration occurs during the formation of phenoxyketone 4a, we added water