Organic synthesis
Catalytic Mitsunobu chemistry with recyclable azo reagents
Open access · cc by · source: Europe PMC
Ethyl arylazocarboxylates plus iron phthalocyanine and air replace stoichiometric DEAD in Mitsunobu esterifications with high inversion.
How this study connects
Role on claims
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This library holds 7 empirical chemistry papers on organic synthesis with isolated findings, rates or spectra rather than reviews.
Evidence for the claim as stated.
Ethyl arylazocarboxylates plus iron phthalocyanine and air replace stoichiometric DEAD in Mitsunobu esterifications with high inversion.
Evidence for the claim as stated.
Study at a glance
- Design
- Animal / in-vitro — Catalytic ethyl arylazocarboxylates reoxidized with O2 and iron phthalocyanine
- N
- Substrate-scope esterifications rather than a single analytic N
- Population
- Secondary alcohols and nucleophiles under Mitsunobu conditions
- Outcome
- Recyclable azo reagents with air as oxidant give high yield and stereochemical inversion, replacing stoichiometric DEAD
Structured fields used in claim comparison tables when every cited study has a complete layer.
Inspect source passages
Catalytic Mitsunobu chemistry with recyclable azo reagents
These passages occur verbatim in the stored paper text. They support the points listed below; they do not verify every statement in the explanation.
Heating THF gave ester 5 in 50% yield and 97% inversion.
The reaction between 3 and 4 in heating THF (65 °C) gave ester product 5 in 50% yield and in 97% inversion (, entry 1).
Toluene at room temperature gave 88% yield and perfect inversion.
To our delight, the reaction in toluene at room temperature provided product 5 in an excellent yield (88%) and in a perfect inversion ratio.
Key findings
Catalyst 1a (3,4-dichlorophenyl) is best for carboxylic acids and stereochemical inversion; 1j (4-cyanophenyl) is best for other nucleophiles. Toluene at RT gave 88% yield with perfect inversion; flame-activated 5 Å sieves gave 94% yield. Air is the sacrificial oxidant.
Methodology
Authors screened ethyl 2-arylhydrazinecarboxylates as catalytic azo sources, reoxidized hydrazines with O2 and iron phthalocyanine, optimized solvent, molecular sieves, and concentration, and measured yield/inversion on secondary alcohols and other nucleophiles.
Limitations
Plant-scale process metrics (E-factor on multi-kilo batches) are not provided; some chlorinated solvents still erode inversion, and PPh3 remains stoichiometric.
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