You can use also other peptide coupling reagents e.g. COMU, TBTU (J. K. Twibanire, T. B. Grindley, Org. Lett., 2011, 13, 2988-2991).
Alternatively you can use Mitsunobu reaction, but purification may be more difficult.
For a methyl ester, dimethyl sulfate and potassium carbonate in DMSO or acetone. Yields are usually quantitative,
For a mild, quantitative method, I have found alkyl halide (e.g. EtBr), in MeCN with potassium carbonate under heating is easy to workup also, with simple filtration and concentration once complete.
All great comments. Agree with Nick that often I go via alkylation using dimethylsulfate with potassium carbonate or even potassium hydrogencarbonate. Probably not the most atom economic but the Mitsunobu reaction / DCC mediated condensation also work very well if your alkylating species is quite complex and an alcohol.
Mix the acid with absolute alcohol, add 2-3 drops of sulfuric acid, wait at room temperature at least 1 hour, and the ester will be formed.
Diazomethan as solution in ether works without any further reagent. It can be prepared without isolation from nitrosomethyl urea or nitrosomethyl-p-toluolsulfonamide in ether by treatment with KOH or NaOH. All acids are converted immediately into the methyl ester but also phenolic OH groups into the methyl ether (tyrosine). Alcoholic OH groups (e.g. from serine) are only converted into the methyl ether in presence of BF3 etherate as catalyst.
There is no best but it really depends on what kind of base compound you have.
You may use 1-tert-butoxy-2-tert-butoxycarbonyl-1,2-dihydroisoquinoline (BBDI) as described in http://dx.doi.org/10.1016/j.tetlet.2004.12.131
OR perhaps via N-hydroxysuccinimide esters!!!
Thank you so much to all for your valuable comments. It really helps me now.
- Badges
- Science topic
- Similar topics
- Chemistry
- Organic Chemistry