L-Glutamine, N²-[(1,1-dimethylethoxy)carbonyl]-4-[[(4-methylphenyl)sulfonyl]oxy]-N-[(2,4,6-trimethoxyphenyl)methyl]-, 1,1-dimethylethyl ester, (4S)-; tert-butyl (2S,4S)-2-((tert-butoxycarbonyl)amino)-5-oxo-4-(tosyloxy)-5-((2,4,6-trimethoxybenzyl)amino)pentanoate; (2S,4R)-4-[¹⁸F]Fluoroglutamine precursor