Tetra-n-butylammonium Fluoride–Catalyzed Eschenmoser–Claisen [3,3]-Sigmatropic Rearrangement

Abstract

Condensation of dibenzofuran and dibenzothiophene carboxaldehydes with various aryl acetic acids followed by esterification of the acid intermediate afforded the 2,3-diaryl acrylates in good overall yields. Reduction of the esters with diisobutylaluminium hydride afforded the allylic alcohols, which underwent a smooth Eschenmoser–Claisen [3,3]-sigmatropic rearrangement on exposure to N,N-dimethylacetamide dimethylacetal in the presence of tetra n-butylammonium fluoride as catalyst to give 3,4-diaryl γ,δ-unstaturated amides in excellent yields.

Keywords:

• Acrylic acids
• allylic alcohols
• Eschenmoser–Claisen rearrangement
• tetra-n-butylammonium fluoride trihydrate
• γ,δ-unstaturated amides

ACKNOWLEDGMENTS

The authors thank Glenmark Pharmaceuticals Limited for granting permission to carry out the present research work.

Notes

^a All reactions were carried out at reflux temperature of the solvents specified in the table.