New Optically Active 4-Alkoxyprolinol Ethers Derived from trans-4-Hydroxy-L-proline

(2S,4R)-trans-4-Hydroxy-L-proline has been used as thechiral-pool source in the efficient syntheses of optically active protected 4-hydroxyprolinols. After N-acyl protection andester formation, the first ether moiety was introduced maintaining the chiral centre adjacent to the ester. Then, reduction of the ester delivered the corresponding carbinol, which had to be alkylated selectively to avoid side reactions with the N-protecting group. Finally, the N-acyl function was removed to generate the target methyl and tert-butyl ethers displaying defined substitution patterns. The so-formed optically active 4-alkoxyprolinol ethers can be used as core fragments in biologically active compounds or …