Methyl iodide → (3aR,5S,6S,7R,7aR)-2-[ethyl(methyl)amino]-6,7-dihydroxy-5,6,7,7a-tetrahydro-3aH-pyrano[3,2-d][1,3]thiazole-5-carboxylic acid

In a 5 mL sure seal vial was added (3aR,5S,6S,7R,7aR)-2-(ethylamino)-6,7-dihydroxy-5,6,7,7a-tetrahydro-3aH-pyrano[3,2-d][1,3]thiazole-5-carboxylic acid (53.00 mg; 0.20 mmol; 1.00 eq.) in N,N-dimethylformamide (2.00 ml) followed by dipotassium carbonate (55.85 mg; 0.40 mmol; 2.00 eq.) and iodomethane (29.69 μl; 0.40 mmol; 2.00 eq.). The mixture was stirred at room temperature for overnight before it was concentrated, purified by Yamazen C1 (40 g column, 220 nm) and dried with lyophilize to afford 7.3 mg (9.3%) monomethylated compound as white solid and two sets of peaks were found on NMR, ratio=3:1.