4CTO:
reference: Glucopyranosylidene-spiro-iminothiazolidinone, a new bicyclic ring system: Synthesis, derivatization, and evaluation for inhibition of glycogen phosphorylase by enzyme kinetic and crystallographic methods., Czifrak K, Pahi A, Deak S, Kiss-Szikszai A, Kover KE, Docsa T, Gergely P, Alexacou KM, Papakonstantinou M, Leonidas DD, Zographos SE, Chrysina ED, Somsak L, Bioorg Med Chem. 2014 Aug 1;22(15):4028-41. doi: 10.1016/j.bmc.2014.05.076. Epub , 2014 Jun 16. PMID: 25009003

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