Regioselective Synthesis of Bioactive Polyheterocycles: Sequential [3, 3] Sigmatropic Rearrangements of 6-(4-Aryloxybut-2-yn-1-yloxy)[1]Benzopyran-2-Ones

Abstract

7a-Methyl-13,13a-dihydro-7aH-furo[3,2-c: 5,4-f]bis-[1]benzopyran-3-ones (4a-d) are regioselectively synthesised in 65–75% yields by the sequential rearrangements of 6-(4-aryloxybut-2-yn-1-yloxy)[1]benzopyran-2-ones (3a-d) in refluxing N, N-diethylaniline (15 h). However, addition of toluene-4-sulphonic acid in the reaction mixture improved the yield (80–85%) and reduced the reaction time (10 h).