Taming the Friedel-Crafts reaction: organocatalytic approach to optically active 2,3-dihydrobenzofurans.

Fine-tuning: Three types of optically active trans-2,3-disubstituted-2,3-dihydrobenzofurans having three contiguous stereogenic centers can be efficiently accessed by one-pot reaction cascades (see scheme; TMS = trimethylsilyl). High substitution diversity of the final products can be achieved from the same common precursors by fine-tuning of their reactivity through simple structural modifications.