# Shiina esterification
**Shiina esterification** is a mild method for forming carboxylic esters and lactones from almost equimolar amounts of a carboxylic acid and an alcohol, using the aromatic anhydride 2-methyl-6-nitrobenzoic anhydride (MNBA) as the dehydrating reagent together with a nucleophilic catalyst such as 4-(dimethylamino)pyridine (DMAP).[1](https://pubs.acs.org/doi/full/10.1021/jo030367x) • [2](https://pdf.benchchem.com/1191/Application_Notes_and_Protocols_for_MNBA_Mediated_Macrolactonization.pdf) It was developed by Isamu Shiina and first reported in 2002 for the macrolactonization of ω-hydroxycarboxylic acids.[3](https://www.sciencedirect.com/science/article/abs/pii/S0040403902018191) • [4](https://triggered.stanford.clockss.org/ServeContent?doi=10.3987%2Fcom-16-13583) In the original formulation, esters are obtained at room temperature in excellent yields with high chemoselectivity using MNBA, triethylamine, and a catalytic amount of DMAP.[1](https://pubs.acs.org/doi/full/10.1021/jo030367x)
| Key fact | Detail |
|---|---|
| Reagent | 2-Methyl-6-nitrobenzoic anhydride (MNBA), with DMAP, 4-pyrrolidinylpyridine (PPY), or DMAP N-oxide (DMAPO) as acyl-transfer catalyst[1](https://pubs.acs.org/doi/full/10.1021/jo030367x) • [5](https://academic.oup.com/bcsj/article-pdf/87/2/196/56276778/bcsj.20130216.pdf) |
| Conditions | Room temperature; solvents dichloromethane or toluene[1](https://pubs.acs.org/doi/full/10.1021/jo030367x) • [6](https://www.tcichemicals.com/assets/cms-pdfs/144drE.pdf) |
| Stoichiometry | Typically 1.3–2.5 equiv MNBA with 2.6–6.0 equiv DMAP in macrolactonization protocols; the original esterification used catalytic DMAP with triethylamine[2](https://pdf.benchchem.com/1191/Application_Notes_and_Protocols_for_MNBA_Mediated_Macrolactonization.pdf) • [1](https://pubs.acs.org/doi/full/10.1021/jo030367x) |
| Model yield | 90% for a model esterification (1.3 equiv MNBA, 3.0 equiv DMAP, CH2Cl2, room temperature, 15 h), versus 67% for Yamaguchi and 36% for Corey–Nicolaou conditions[5](https://academic.oup.com/bcsj/article-pdf/87/2/196/56276778/bcsj.20130216.pdf) |
| Macrolactonization | Slow syringe-pump addition of the seco acid at ~1–2 mM gives macrolactones in high yield; a 16-membered ring was obtained in 95% at room temperature in 1 h[6](https://www.tcichemicals.com/assets/cms-pdfs/144drE.pdf) • [2](https://pdf.benchchem.com/1191/Application_Notes_and_Protocols_for_MNBA_Mediated_Macrolactonization.pdf) |
| Ring sizes | β-Lactones, 8-membered rings, and 16-membered macrolactones and macrolactams have all been made[7](https://pubs.acs.org/acsodf/article-pdf/6/5/3571/19361525/ao0c04878.pdf) • [8](https://www.jstage.jst.go.jp/article/yukigoseikyokaishi1943/63/1/63_1_2/_article) |
| Availability | MNBA is sold commercially (Sigma-Aldrich product 681059) as a coupling promoter for amides, lactones, esters, and peptides[9](https://www.sigmaaldrich.com/ZA/en/product/aldrich/681059) |
## Reagents and mechanism
The reaction runs through a mixed anhydride. In the catalytic cycle described by Shiina, DMAP first attacks MNBA to form a pyridinium salt (INT-1) of 2-methyl-6-nitrobenzoic acid. The substrate carboxylic acid then reacts with INT-1 to form the mixed anhydride, so the acid itself participates in activating the reagent rather than waiting as a passive partner. A second acyl-pyridinium salt (INT-2) forms by chemoselective nucleophilic substitution, and the substrate alcohol attacks INT-2 to give the ester and regenerate DMAP. All steps in the cycle are reversible except the final ester-forming step through the transition state.[4](https://triggered.stanford.clockss.org/ServeContent?doi=10.3987%2Fcom-16-13583) Density functional calculations on β-lactone formation support a concerted final stage in which the in-situ-formed 2-methyl-6-nitrobenzoate anion deprotonates the substrate hydroxy group as the lactone closes.[7](https://pubs.acs.org/acsodf/article-pdf/6/5/3571/19361525/ao0c04878.pdf)
The reaction is promoted by acyl-transfer catalysts including DMAP, PPY, and DMAPO.[5](https://academic.oup.com/bcsj/article-pdf/87/2/196/56276778/bcsj.20130216.pdf) In the FE399 depsipeptide synthesis, a combination of MNBA with catalytic DMAPO (0.2 equiv) and triethylamine gave the best macrolactamization yield, and MNBA/DMAPO outperformed the peptide coupling reagents HATU and PyBOP under the same conditions.[7](https://pubs.acs.org/acsodf/article-pdf/6/5/3571/19361525/ao0c04878.pdf)
**Why the 2-methyl-6-nitro pattern matters.** Control experiments showed that the isomeric anhydrides 2-nitrobenzoic, 3,4-dinitrobenzoic, and 3,5-dinitrobenzoic anhydride gave the model ester in only 70%, 65%, or lower yields, so the tested alternatives did not match MNBA's yield for this model ester.[5](https://academic.oup.com/bcsj/article-pdf/87/2/196/56276778/bcsj.20130216.pdf) Variants extend the toolkit: 2,6-dimethyl-4-nitrobenzoic anhydride (DMNBA), introduced in 2008, works under both acidic and basic conditions,[10](https://triggered.edinburgh.clockss.org/ServeContent?doi=10.3987%2Fcom-08-s%28n%2996) and 2-fluoro-6-(trifluoromethyl)benzoic anhydride (FTFBA) was identified as a complementary dehydrating agent with DMAP, giving esters and lactones in high yields with high product selectivity.[4](https://triggered.stanford.clockss.org/ServeContent?doi=10.3987%2Fcom-16-13583) An earlier, related method used 4-(trifluoromethyl)benzoic anhydride (TFBA) with Lewis acid catalysts.[5](https://academic.oup.com/bcsj/article-pdf/87/2/196/56276778/bcsj.20130216.pdf) • [8](https://www.jstage.jst.go.jp/article/yukigoseikyokaishi1943/63/1/63_1_2/_article)
## Scope and typical conditions
The reaction proceeds smoothly at room temperature from nearly equimolar amounts of acid and alcohol, which minimizes excess reagent and simplifies purification.[1](https://pubs.acs.org/doi/full/10.1021/jo030367x) • [4](https://triggered.stanford.clockss.org/ServeContent?doi=10.3987%2Fcom-16-13583) [Dichloromethane](https://www.edgepedia.org/dichloromethane) and toluene are the standard solvents.[6](https://www.tcichemicals.com/assets/cms-pdfs/144drE.pdf) In the model esterification comparison, 1.3 equiv MNBA with 3.0 equiv DMAP in dichloromethane at room temperature for 15 h gave 90%; the DMNBA variant and an MNBA/PPY variant each gave 87%.[5](https://academic.oup.com/bcsj/article-pdf/87/2/196/56276778/bcsj.20130216.pdf) Reaction times range from minutes to about a day: the FE399 macrolactamization reached good yield in 5 minutes and 69% in 1 hour.[7](https://pubs.acs.org/acsodf/article-pdf/6/5/3571/19361525/ao0c04878.pdf)
## Macrolactonization
Macrolactonization of ω-hydroxycarboxylic acids (seco acids) is the method's signature application. The practical protocol calls for slow, high-dilution addition: a solution of the seco acid in dichloromethane or toluene is added by [syringe pump](https://www.edgepedia.org/syringe-pump) over 4–12 hours at room temperature to a solution of MNBA and DMAP, at a final substrate concentration of roughly 1–2 mM. The slow addition is critical for maximizing monomeric macrolactone yield.[6](https://www.tcichemicals.com/assets/cms-pdfs/144drE.pdf) • [2](https://pdf.benchchem.com/1191/Application_Notes_and_Protocols_for_MNBA_Mediated_Macrolactonization.pdf) Adding the seco acid to a mixture of MNBA and promoters at a suitable temperature affords macrolactones in excellent yields with high purity.[4](https://triggered.stanford.clockss.org/ServeContent?doi=10.3987%2Fcom-16-13583)
Ring sizes from small to large are accessible: β-lactones, the 8-membered lactone moieties of octalactins A and B and cephalosporolide D, and 16-membered macrolactones and macrolactams.[1](https://pubs.acs.org/doi/full/10.1021/jo030367x) • [7](https://pubs.acs.org/acsodf/article-pdf/6/5/3571/19361525/ao0c04878.pdf) • [8](https://www.jstage.jst.go.jp/article/yukigoseikyokaishi1943/63/1/63_1_2/_article) Conformation of the seco acid governs the outcome. In the erythromycin A aglycon (erythronolide A) work, conformationally appropriate seco acids gave the monomeric lactone in excellent yield under mild conditions; a highly strained substrate still cyclized in relatively good yield at 100 °C in toluene; and a seco acid with a stable linear conformation dimerized, giving the diolide in high yield with a constant monomer-to-dimer ratio of approximately 1/5.[11](https://onlinelibrary.wiley.com/doi/10.1002/tcr.200900017)
## By the numbers
- **Model esterification:** 90% yield with 1.3 equiv MNBA and 3.0 equiv DMAP in CH2Cl2 at room temperature for 15 h.[5](https://academic.oup.com/bcsj/article-pdf/87/2/196/56276778/bcsj.20130216.pdf)
- **Macrolactonization loadings:** 1.3–2.5 equiv MNBA with 2.6–6.0 equiv DMAP, or catalytic-to-stoichiometric DMAPO.[2](https://pdf.benchchem.com/1191/Application_Notes_and_Protocols_for_MNBA_Mediated_Macrolactonization.pdf)
- **Dilution:** about 1–2 mM final substrate concentration, with syringe-pump addition over 4–12 h.[2](https://pdf.benchchem.com/1191/Application_Notes_and_Protocols_for_MNBA_Mediated_Macrolactonization.pdf)
- **Representative macrolactone yields:** 15-hydroxypentadecanoic acid (16-membered ring) gave 95% in CH2Cl2 at room temperature in 1 h with 6.0 equiv DMAP; 11-hydroxyundecanoic acid gave 89% in CH2Cl2 at room temperature in 3 h; the smaller-ring 9-hydroxynonanoic acid required toluene at 100 °C for 18–24 h and gave 67–71%.[2](https://pdf.benchchem.com/1191/Application_Notes_and_Protocols_for_MNBA_Mediated_Macrolactonization.pdf)
- **FE399 macrolactamization:** 1.3 equiv MNBA and 2.6 equiv DMAP in dichloromethane at 2 mM gave 62%, reaching 69% within 1 h.[7](https://pubs.acs.org/acsodf/article-pdf/6/5/3571/19361525/ao0c04878.pdf)
One point of practice varies between sources: the original papers describe DMAP or DMAPO as a catalytic additive with triethylamine,[1](https://pubs.acs.org/doi/full/10.1021/jo030367x) • [3](https://www.sciencedirect.com/science/article/abs/pii/S0040403902018191) while published macrolactonization protocols use 2.6–6.0 equivalents of DMAP with 1.3–2.5 equivalents of MNBA.[2](https://pdf.benchchem.com/1191/Application_Notes_and_Protocols_for_MNBA_Mediated_Macrolactonization.pdf) Both usages appear in the literature; the larger DMAP loadings belong to the macrolactonization protocols rather than the original intermolecular esterification.
## How it compares with other esterification methods
In head-to-head comparisons published by the Shiina group, MNBA conditions outperformed the classical alternatives on the same substrates. For a difficult dilactone, Corey–Nicolaou conditions (PySSPy/PPh3, toluene, 80 °C) gave 13–18%, Yamaguchi conditions (TCBC/Et3N/DMAP, toluene reflux) gave 0–10%, and Keck–Steglich conditions (DCC/DMAP·HCl, CHCl3 reflux) gave 23%, while Shiina MNBA (1.3 equiv, 6.0 equiv DMAP, toluene, 20 °C, 19 h) gave 58%, rising to 62% with 1.5 equiv MNBA and molecular sieves at 23 °C for 23 h.[5](https://academic.oup.com/bcsj/article-pdf/87/2/196/56276778/bcsj.20130216.pdf) For an intermolecular esterification, Corey–Nicolaou gave 36% and Yamaguchi (toluene, 60 °C, 16 h) gave 67%, against 90% for MNBA/DMAP at room temperature.[5](https://academic.oup.com/bcsj/article-pdf/87/2/196/56276778/bcsj.20130216.pdf) The two Yamaguchi figures reflect different substrates and temperatures rather than a contradiction: the Yamaguchi method performs well on some esterifications but can fail or decompose substrates on demanding macrolactonizations, a limitation also noted in a 2024 review, which cites the steric environment of 2,4,6-trichlorobenzoyl chloride (TCBC) as limiting its reactivity.[12](https://www.frontiersin.org/journals/chemistry/articles/10.3389/fchem.2024.1477764/full)
Against other reagent families, the practical contrasts are mildness and byproducts. [Yamaguchi esterification](https://www.edgepedia.org/yamaguchi-esterification) generally requires higher temperatures with stoichiometric reagent; the [Mitsunobu reaction](https://www.edgepedia.org/mitsunobu-reaction) needs a stoichiometric phosphine and gives byproducts that can be difficult to remove; and the Mukaiyama reagent is moisture-sensitive.[2](https://pdf.benchchem.com/1191/Application_Notes_and_Protocols_for_MNBA_Mediated_Macrolactonization.pdf) In the FE399 work, MNBA with catalytic DMAPO showed much higher activity than HATU and PyBOP under identical conditions.[7](https://pubs.acs.org/acsodf/article-pdf/6/5/3571/19361525/ao0c04878.pdf)
## Applications in synthesis
Named targets made with MNBA-mediated couplings span large, medium, and small lactones: (+)-ricinelaidic acid lactone, threo- and erythro-aleuritic acid lactone, (−)-cephalosporolide D, (−)-octalactin A and B, 2-epibotcinolide, 2-hydroxytetracosanolides, (−)-tetrahydrolipstatin, and erythromycin A skeletons.[5](https://academic.oup.com/bcsj/article-pdf/87/2/196/56276778/bcsj.20130216.pdf) • [1](https://pubs.acs.org/doi/full/10.1021/jo030367x) The method was applied to the synthesis of erythro-aleuritic acid lactone and the eight-membered-ring lactone moiety of octalactins A and B.[1](https://pubs.acs.org/doi/full/10.1021/jo030367x)
The method also extends beyond lactones. In the total synthesis of (9R,14R,17R)-(−)-FE399, a bicyclic depsipeptide of pharmaceutical interest, MNBA-mediated macrolactamization formed the 16-membered macrolactam core, the first application of MNBA-mediated macrolactamization in the total synthesis of natural products.[7](https://pubs.acs.org/acsodf/article-pdf/6/5/3571/19361525/ao0c04878.pdf) In the total synthesis of (+)-prunustatin A, Shiina MNBA couplings formed each of the four ester bonds of the tetralactone ring, including the key macrocyclization, which was chosen to minimize competing Thorpe–Ingold-effect-accelerated transesterification.[13](https://pubmed.ncbi.nlm.nih.gov/30160125/) MNBA is commercially available from [Sigma-Aldrich](https://www.edgepedia.org/sigma-aldrich) as a coupling promoter for amides, lactones, esters, and peptides, described as a versatile lactonization reagent for macrolide natural product preparation.[9](https://www.sigmaaldrich.com/ZA/en/product/aldrich/681059)
## References
1. [Isamu Shiina and colleagues (2003). An Effective Use of Benzoic Anhydride and Its Derivatives for the Synthesis of Carboxylic Esters and Lactones. Journal of Organic Chemistry.](https://pubs.acs.org/doi/full/10.1021/jo030367x)
2. [Application Notes and Protocols for MNBA-Mediated Macrolactonization. BenchChem.](https://pdf.benchchem.com/1191/Application_Notes_and_Protocols_for_MNBA_Mediated_Macrolactonization.pdf)
3. [Shiina and colleagues (2002). A novel and efficient macrolactonization of ω-hydroxycarboxylic acids using 2-methyl-6-nitrobenzoic anhydride (MNBA). Tetrahedron Letters.](https://www.sciencedirect.com/science/article/abs/pii/S0040403902018191)
4. [Isamu Shiina (2016). Various Synthetic Methods Using Aromatic Carboxylic Anhydrides. HETEROCYCLES.](https://triggered.stanford.clockss.org/ServeContent?doi=10.3987%2Fcom-16-13583)
5. [Isamu Shiina (2014). An Adventurous Synthetic Journey with MNBA from Its Reaction Chemistry to the Total Synthesis of Natural Products. Bulletin of the Chemical Society of Japan.](https://academic.oup.com/bcsj/article-pdf/87/2/196/56276778/bcsj.20130216.pdf)
6. [Various Synthetic Methods Using Aromatic Carboxylic Anhydrides. TCI technical note.](https://www.tcichemicals.com/assets/cms-pdfs/144drE.pdf)
7. [MNBA in the Synthesis of the Depsipeptidic Analogue of FE399. ACS Omega.](https://pubs.acs.org/acsodf/article-pdf/6/5/3571/19361525/ao0c04878.pdf)
8. [Shiina. An Effective Use of Benzoic Anhydride and Its Derivatives. Yuki Gosei Kagaku Kyokaishi.](https://www.jstage.jst.go.jp/article/yukigoseikyokaishi1943/63/1/63_1_2/_article)
9. [2-Methyl-6-nitrobenzoic anhydride, product 681059. Sigma-Aldrich.](https://www.sigmaaldrich.com/ZA/en/product/aldrich/681059)
10. [Shiina and colleagues (2008). 2,6-Dimethyl-4-nitrobenzoic Anhydride (DMNBA): An Effective Coupling Reagent for the Synthesis of Carboxylic Esters and Lactones. HETEROCYCLES 76.](https://triggered.edinburgh.clockss.org/ServeContent?doi=10.3987%2Fcom-08-s%28n%2996)
11. [Shiina and colleagues (2009). Evaluation of the Efficiency of the Macrolactonization Using MNBA in the Synthesis of Erythromycin A Aglycon. The Chemical Record.](https://onlinelibrary.wiley.com/doi/10.1002/tcr.200900017)
12. [Yamaguchi esterification: a key step toward the synthesis of natural products and their analogs, a review (2024). Frontiers in Chemistry.](https://www.frontiersin.org/journals/chemistry/articles/10.3389/fchem.2024.1477764/full)
13. [Total Synthesis of (+)-Prunustatin A (2018). PubMed record.](https://pubmed.ncbi.nlm.nih.gov/30160125/)
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*Topic: Encyclopedia › Physical world and mathematics › Chemistry › Organic substances › Organic reactions, structure and reference › Synthetic reagents, protecting groups, and acyl methods › Esterification and acyl substitution methods › Mild and coupling-reagent esterification*
*Initially written Sep 17, 2026 · Reviewed: Oct 15, 2026 · Edited: Oct 15, 2026 · Last review: Oct 15, 2026*
*Copyright 2026 EdgeChat AI, a subsidiary of Biostate AI.*
License: Edgepedia Community License 1.0, https://www.edgepedia.org/edgepedia/license