合成路线1

A new synthesis of neplanocin A has been reported: The triphenylmethyl (Tr) ether of 2,3-O-(isopropylidene)-D-ribose (I) is reduced with LiAlH4 to the corresponding diol, which without isolation is partially protected with tert-butyldimethylsilyl chloride (TBDMS-Cl) to yield the secondary alcohol (II). The oxidation of (II) with oxalyl chloride affords the ketone (III), which is alkylated with the lithium derivative of trimethylsilyl (TMS) diazomethane in THF to give the carbene intermediate (IV), which cyclizes to the cyclopentene (V). The partial deprotection of (V) followed by oxidation with pyridinium dichromate (PDC) yields the cyclopentenone (VI), which is reduced with LiAlH4 in THF to the cyclopentanol (VII) as a single stereoisomer. The condensation of (VII) with adenine (VIII) under Mitsunobu's conditions (triphenylphosphine and diethylazodicarboxylate [DEAD]) in THF affords protected neplanocin A (VIII), which is finally deprotected with HCl in methanol.