| Abstract
| - The first total synthesis of one of the spicamycin congeners, SPM VIII (3), is described. A preliminarymodel study for construction of the characteristic N-glycoside linkage in spicamycin using tetra-O-benzyl-β-d-mannopyranosylamine (13) and halopurines 5 revealed that Pd-catalyzed conditionssuccessfully provided the coupling products 14 and 15 in good yields. It was also shown that thermalanomerization of the N-glycosides easily occurred, which resulted in the predominant formation ofthe β-anomer as the thermodynamically favored compound, and the activation energy of anomerization of 15 was estimated to be ca. 30 kcal/mol. The novel aminoheptose unit of spicamycin 6was prepared stereoselectively by carbon elongation of an acyclic aldehyde, prepared by ring cleavagereaction of a highly functionalized cyclohexane derived from naturally abundant myo-inositol. ThePd-catalyzed coupling reaction of the β-heptopyranosylamine 6 with protected 6-chloropurine 5d,followed by deprotection, provided spicamycin amino nucleoside 2, whose condensation withdodecanoylglycine completed the total synthesis of 3. This study confirmed the proposed uniquestructure of a novel nucleoside antibiotic.
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