合成路线1

The oxidation of mannitol diacetonide (I) with Pb(OAc)4 in benzene gives the glyceraldehyde acetonide (II), which is reductocondensed with benzylamine (III) by means of H2 over Pd/C in methanol to yield, after acidification with HCl, (S)-3-(benzylamino)propane-1,2-diol (IV). The cyclization of (IV) with benzaldehyde (V) in refluxing toluene affords the chiral oxazolidine (VI), which is treated with tosyl chloride and pyridine to provide the corresponding tosylate (VII). The condensation of (VII) with 4-[2-(cyclopropylmethoxy)ethyl]phenol (VIII) by means of NaH in DMF gives the phenolic ether (IX), which is treated with conc. HCl to open the oxazolidine ring and yield the chiral propanolamine (X). The alkylation of the secondary amino group of (X) with isopropyl iodide (XI) in refluxing ethanol affords the tertiary amine (XII), which is debenzylated by hydrogenation with H2 over Pd/C in ethanol to provide the target betaxolol.