Synthesis of enantiomerically pure alpha-[14C]methyl-L-tryptophan.
A practical method for the preparation of large amounts of enantiomerically pure alpha-[14C]methyl-L-tryptophan using the enzymatic resolution of the corresponding D,L-methyl ester is reported. The radiolabelled alpha-methyl group was introduced using the alpha-methylation of the lithium enolate of the Schiff base of L-tryptophan methyl ester. Hydrolysis of the Schiff base with 1N HCl provided the D,L-methyl ester of alpha-[14C]methyl tryptophan. Enantioselective enzymatic hydrolysis of the L-methyl ester by alpha-chymotrypsin gave the enantiomerically pure alpha-[14C]methyl-L-tryptophan. The overall yield of this preparation was 33%.
Mzengeza
S
S
Montreal Neurological Institute, McGill University, Canada.
Venkatachalam
T K
TK
Rajagopal
S
S
Diksic
M
M
D002250:Carbon Radioisotopes; D007553:Isotope Labeling; D014364:Tryptophan / Q000031:analogs & derivatives* / Q000138:chemical synthesis
D002250:Carbon Radioisotopes; C020774:alpha-methyltryptophan; D014364:Tryptophan