Photoresist Chemicals L-Cysteine, S-[(2R,3R,4S)-2-(3,4-dihydroxyphenyl)-3,4-dihydro-3,5,7-trihydroxy-2H- 1-benzopyran-4-yl]-, ethyl ester Cas:876519-96-9 Molecular Formula:C20H23NO8S