Problema 19 Pyrrolizidine alkaloids Very recently, the first total
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Problema 19 Pyrrolizidine alkaloids Very recently, the first total
www.pianetachimica.it Problema 19 Pyrrolizidine alkaloids Very recently, the first total synthesis of nigricanin, one of the ellagic acid congeners, was described. Decipher this scheme. Write down the structural formulae of compounds A–K accounting for the facts that F and G are isomers; molecular formulae of D and E are C21H17IO4 and C37H31IO7, respectively. Soluzione: OH HO OH OH BnO BnO H O ICl piridina TsOH benzene ∆ O O A OBn OH BnO I BnO BnBr H OBn I K2CO3 I NaH2PO4 H O BnO NaClO2 OH O B EDC DMAP O C O A D O O O H 1) Pd(OAc)2 AcONa BnO PPh3 O BnO I 2) H3O O OBn O E 47 IChO 2015 Baku – Azerbaijan BnO OBn O OBn O H + O O BnO O F G Soluzioni preliminari dei problemi preparatori 1 www.pianetachimica.it OH O H O OBn H2 , Pd/C BnO OBn HO OH CH3OH O O O O nigricanin F O O OH BnO O MOMCl BnO I H O I NR3 NaClO2 H O BnO I NaH2PO4 OH O B O EDC DMAP O H O A I O O O H O 1) Pd(OAc)2 AcONa, PPh3 I BnO 2) H3O O O BnO OBn + O H2 , Pd/C CH3OH OBn O O J K OH O HO OH O O nigricanin Soluzione proposta da Mauro Tonellato - ITI Marconi - Padova 47 IChO 2015 Baku – Azerbaijan Soluzioni preliminari dei problemi preparatori 2