[56530-39-3] · C15H11NO5S · N-(p-Toluenesulfonyloxy)phthalimide · (MW 317.34)
(transformation of aryllithiums and enolates into 3,3-disubstituted quinoline-2,4-diones1)
Alternate Name: N-tosyloxyphthalimide.
Physical Data: mp 161-162 °C.
Solubility: sol ether, THF; slightly sol alcohol.
For carbanion amination, various O-sulfonylhydroxylamines have been used,4 and Grignard reagents, organolithiums, and enolates have been converted into primary and tertiary amines (eq 1).
However, the reactions of aryl carbanions and enolates with N-tosyloxyphthalimide gives 3,3-disubstituted quinoline-2,4-diones (eq 2) in moderate to good yields (eqs 3 and 4).1
The reaction is carried out as follows. Aryllithium or enolate is prepared by using n-Butyllithium at -70 °C in THF and a solution of N-tosyloxyphthalimide (0.5 equiv) is added with stirring. Stirring is continued until the temperature reaches 15 °C, when the solution is poured into aqueous acid. After extraction with dichloromethane and evaporation, the residue is crystallized.
The proposed mechanism involves the possible intermediate isocyanato ketone, which is attacked by the carbanion to form another carbanion which then undergoes intramolecular attack at the carbonyl group, leading to cyclization to form the dione (eq 5).
Ankara University, Turkey