What are the by products when a Boc protected Amino Acid carboxylic acid reacts with an alcohol in presence of thionyl chloride to produce an ester hydrochloride salt? How does the N-Boc is broken and what are its products?
Kona
Thionyl chloride reacts with alcohol and water to produce HCl and deprotect N-Boc to form t-butyl cation which undergoes elimination or substitution reactions.
See
---https://www.organic-chemistry.org/protectivegroups/amino/boc-amino.htm
for your transformation take a look at the enclosed file
Good luck
Adel Amer
Thank you very much. I got many things out of your answer. But still I would like to know the list of by products formed in this reaction. Because such reactions must be carried out with better safety precautions.
Kona
"The tert-butyl cation will either be quenched by a suitable trapping agent (during the work up), deprotonate to form isobutylene (gas), or polymerize to form isobutylene oligomers. The CO2 gas that forms during the reaction should be allowed to escape. Don't run boc deprotections in closed systems."
Good luck
You might try adding the BOC-protected amino acid to DMF or CH3CN which has 2 eq of triethylamine and 1.1 eq dimethylsulfate or methyl iodide in it. Let it stir overnight at RT and monitor by TLC or LCMS. When reaction is complete, use an aqueous NaHCO3 workup to keep the pH slightly basic while extracting with ether. Evaporate off the Et3N and finish with a chromatography on silica gel.