合成路线1

A different synthetic strategy used 3,4:5,6-O-diisopropylidene-D-mannitol (VI) as the starting material. Dehydration of (VI) by means of dimethylformamide dimethylacetal and Ac2O provided olefin (VII). Selective hydrolysis of the terminal acetonide of (VII) was achieved by means of 80% AcOH to afford diol (VIII). Conversion of (VIII) to the primary tosylate (IX), followed by treatment with Na2CO3 gave epoxide (X). Oxirane ring opening in (X) with NaCN furnished the beta-hydroxy nitrile (XI). This was then protected as the unsymmetric acetal (XII) by acid-catalyzed addition of ethyl vinyl ether. Partial reduction of the nitrile function of (XII) with DIBAL in toluene at -78 C gave rise to aldehyde (XIII), which was further derivatized as the corresponding oxime (XIV). The nitrile oxide generated by treatment of oxime (XIV) with NaOCl and Et3N underwent a dipolar cycloaddition to the olefin, leading to isoxazoline (XV)