合成路线1

The intermediate lactone (VII) was prepared as follows. Alpha-D-glucoheptonic gamma-lactone (I) was converted to the bis(acetonide) (II) by treatment with I2 in acetone. Methylation of the free hydroxyl group of (II) using Ag2O and methyl iodide provided the methyl ether (III). Selective removal of 1,2-acetonide of (III) in the presence of the 1,3-acetonide was accomplished by treatment of (III) with acetic acid. The resulting vicinal diol (IV) was then subjected to oxidative cleavage with NaIO4 to produce aldehyde (V). This was then olefinated with the low-valent organochromium species generated in situ from 1,1-diiodoisobutane (VI) and CrCl2 to produce the E-olefin (VII) as the major isomer, which was isolated using preparative HPLC.