An Oxidation Study of Phthalimide-Derived Hydroxylactams
Bernard L Adjei1, Frederick A Luzzio1
1Department of Chemistry, University of Louisville, 2320 South Brook Street, Louisville, KY 40292, USA.
Molecules (Basel, Switzerland)
|January 21, 2022
Summary
Nickel peroxide efficiently oxidizes hydroxylactams to phthalimides. This study compares nickel peroxide, pyridinium chlorochromate, and iodoxybenzoic acid for hydroxylactam oxidation, finding nickel peroxide effective for phthalimide synthesis.
Area of Science:
- Organic Chemistry
- Synthetic Chemistry
- Oxidation Reactions
Background:
- Hydroxylactams are precursors to phthalimides, important heterocyclic compounds.
- Efficient oxidation methods are crucial for synthesizing phthalimides from hydroxylactams.
Purpose of the Study:
- To systematically study the oxidation of 3-hydroxy-2-substituted isoindolin-1-ones (hydroxylactams) to phthalimides.
- To introduce and evaluate nickel peroxide (NiO2) as an oxidant for this transformation.
- To compare the efficacy of NiO2 with pyridinium chlorochromate (PCC) and iodoxybenzoic acid (IBX).
Main Methods:
- Oxidation of various hydroxylactams using three different oxidants: NiO2, PCC, and IBX.
- Optimization of reaction conditions for NiO2, including solvent (toluene), temperature (reflux), and equivalents (50).
- Comparison of reaction times, purification procedures, and yields across the three oxidation methods.
Main Results:
- Nickel peroxide (NiO2) effectively converted hydroxylactams to phthalimides in 5-32 hours.
- Pyridinium chlorochromate (PCC) and iodoxybenzoic acid (IBX) required shorter reaction times (1-3 hours) but involved lengthier purification.
- All three methods demonstrated good to excellent isolated yields upon scale-up.
Conclusions:
- Nickel peroxide is a viable and effective oxidant for the conversion of hydroxylactams to phthalimides.
- The choice of oxidant (NiO2, PCC, or IBX) impacts reaction time and purification complexity.
- The studied methods are suitable for the synthesis of phthalimides, with potential for scale-up.
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