Unprecedented synergistic effects between weak Lewis and Brønsted acids in Prins cyclization
作者:Prashant Borkar、Pierre van de Weghe、B. V. Subba Reddy、J. S. Yadav、René Grée
DOI:10.1039/c2cc35052a
日期:——
Novel synergistic effects between Lewis and Brønsted acids in Prins cyclization are reported. Non-reactive Lewis acids and non-reactive Brønsted acids, which failed to perform Prins cyclization when used alone, have shown remarkable synergistic effects when used in combination to perform the reaction successfully.
Rapid and Efficient Protocol for the Synthesis of 4-Chlorotetrahydropyrans Using Niobium(V) Chloride
作者:J. S. Yadav、B. V. Reddy、Manoj Kumar Gupta、Swapan Kumar Biswas
DOI:10.1055/s-2004-831220
日期:——
Aldehydes undergo a rapid coupling with 3-buten-1-ol utilizing 20 mol% of niobium(V) chloride to afford 4-chlorotetrahydropyran derivatives under extremely mild conditions within short reaction times in excellent yields with high selectivity. The similar halogenated tetrahydropyrans are also obtained using gallium(III) halides.