合成路线1

Synthesis of intermediate (LXIII): The reaction of aldehyde (LVI) with (-)-diisopinocampheyl-(E)-crotyl boronate (DIPCB) in toluene gives the chiral alcohol (LVII), which is protected with Bn-Br and NaH, yielding the benzyl ether (LVIII).The oxidation of the terminal double bond of (LVIII) with OsO4 and NaIO4 in THF/methanol/water affords the aldehyde (LIX), which is treated with (R,R)-diisopropyl allyl boronate (DISAB) to provide the allylic alcohol (LX). The silylation of (LX) with Tips-OTf, followed by debenzylation with Li/NH3 gives the secondary alcohol (LXI). The oxidation of the terminal double bond of (LXI) with OsO4 and NaIO4, with simultaneous cyclization yields the dihydropyran derivative (LXII), which is finally iodinated with n-BuLi, Bu3Sn-Cl and N-iodosuccinimide (NIS) in THF to afford the desired iodinate dihydropyran intermediate (LXIII).