6-exo-trig Michael addition-lactonizations for catalytic enantioselective chromenone synthesis.
Rifahath M NeyyappadathDavid Bradford CordesAlexandra M Z SlawinAndrew David SmithPublished in: Chemical communications (Cambridge, England) (2018)
The catalytic enantioselective 6-exo-trig Michael addition-lactonization of enone-acid substrates to form cis-chromenones with high diastereo- and enantiocontrol was developed using the commercially available isothiourea tetramisole. An acidic workup proved necessary to minimize product epimerization and maximize product er, providing cis-chromenones in excellent yield, and with excellent diastereo- and enantioselectivity.