Enantioselective, Catalytic Fluorolactonization Reactions with a Nucleophilic Fluoride Source
The enantioselective synthesis of 4-fluoroisochromanones via chiral aryl iodide-catalyzed fluorolactonization is reported. This methodology uses HF-pyridine as a nucleophilic fluoride source with a peracid stoichiometric oxidant and provides access to lactones containing fluorine-bearing stereogenic centers in high enantio- and diastereoselectivity. The regioselectivity observed in these lactonization reactions is complementary to that obtained with established asymmetric electrophilic fluorination protocols.
Woerly, Eric M.,Banik, Steven M.,Jacobsen, Eric N.
Enantiodifferentiating endo-selective oxylactonization of ortho-alk-l-enylbenzoate with a lactate-derived aryl-λ3-iodane
It's the hype: The asymmetric synthesis of 3-alkyl-4-oxyisochroman-1-one is achieved by oxylactonization of ortho-alk-1-enylbenzoate with a series of optically active hypervalent iodine(III) reagents prepared from lactate or valine as a chiral source (see scheme). The oxylactonization is highly regio-, diastereo-, and enantioselective. 2010 Wiley-VCH Verlag GmbH & Co. KGaA.