Hydrogen Bromide → HCID 70376230, compound

Participants

Reaction Steps

2,6-Dimethyl-(S)-tyrosine hydrobromide was prepared by deprotecting N-acetyl-2,6-dimethyl-O-methyl-(S)-tyrosine methyl ester as follows: In a 100 ml round-bottom flask were placed 18.56 g (66 mmol) of N-acetyl-2,6dimethyl-O-methyl-(S)-tyrosine methyl ester, 0.63 g (3.3 mmol) sodium metabisulfite, 43 ml 48% hydrobromide acid and 21 ml acetic acid. After flushing with nitrogen, the flask was immersed in an oil bath at 120° C. and maintained there for 15 hours. After cooling, the volatiles were removed under reduced pressure at 100° C. to afford a tan solid of the desired product, contaminated with sodium metabisulfite. A sample was derivatized with Marfey's reagent and shown by HPLC analysis to be a 99.7/0.3 mixture of S and R isomers, respectively. 1H NMR analysis indicated: (δ, CD3OD) 6.55 (s, 2H), 4.07 (br t, J=7.5 Hz, 1H), 3.32 (dd, J=7.5 and 14.1 Hz, 1H), 3.15 (dd, J= 7.5 and 14.1 Hz, 1H) and 2.31 (s, 6H). Mass spectrum analysis indicated: 209 (M+), 135 (100%) and 91.

Provenance & Evidence