Direct Nucleophilic Acylation of Nitroalkenes Promoted by a Fluoride Anion/Thiourea Combination

The direct nucleophilic acylation of nitroalkenes is reported utilizing a fluoride-initiated rearrangement of protected thiazolium carbinols. The key combination of fluoride anion and thiourea accesses carbonyl anion reactivity without the use of amine or amide bases typically employed in the generation of these Umpolung nucleophiles. The mild reaction conditions used to generate the reactive carbonyl anion species in situ allow for conjugate additions in good yield to sensitive nitroalkene electrophiles. The process is tolerant of a variety of thiazolium carbinols and nitroalkene substrates and can be rendered enantioselective and diastereoselective by the addition of a chiral thiourea derived from quinine.