Lipase-catalyzed enantioselective esterification of mono-aza-benzo-15-crown-5-ether derivatives in organic media.
For the purpose of developing a new chiral crown ether unit as a chiral synthon, three racemic mono azabenzo-15-crown-5-ethers, i.e. (R,S)-1-(6,7,9,10,12,13,15,16-octahydro-5,8,14,17-tetraoxa-11-aza-benzocyclopentadecen-11-yl)-propan-2-ol, (R,S)-2-(6,7,9,10,12,13,15,16-octahydro-5,8,14,17-tetraoxa-11-aza-benzocyclopentadecen-11-yl)-1-phenyl-ethanol and (R , S)-1-[2-(6,7,9,10,12,13,15,16-octahydro-5,8,14,17-tetraoxa-11-aza-benzocyclopentadecen-11-ylmethyl)-phenyl]-ethanol were esterified with vinyl acetate using a lipase from Candida antarctica. The enzymatic acylation of alcohols produced monoacylated products. Two optically active azacrown ethers, (R)-propionic acid 1-methyl-2-(6,7,9,10,12,13,15,16-octahydro-5,8,14,17-tetraoxa-11-aza-benzocyclopentadecen-11-yl)-ethyl ester and (R)-acetic acid 1-[2-(6,7,9,10,12,13,15,16-octahydro-5,8,14,17-tetraoxa-11-aza-benzocyclopentadecen-11-ylmethyl)-phenyl]-ethyl ester were obtained within 48% and 36% yields, respectively and, at an enantiometric excess of over 99% in each case.
Kijima
Tatsuro
T
Department of Chemistry and Chemical Engineering, Faculty of Engineering, Yamagata University, 4-3-16 Jonan, Yonezawa, Yamagata 992-8510, Japan. kijima@yz.yamagata-u.ac.jp
Sato
Noriyasu
N
Izumi
Taeko
T
D002384:Catalysis; D043844:Crown Ethers / Q000737:chemistry*; D004951:Esterification; D007536:Isomerism; D008049:Lipase / Q000737:chemistry*; D009930:Organic Chemicals / Q000737:chemistry*; D012680:Sensitivity and Specificity
D043844:Crown Ethers; D009930:Organic Chemicals; C042148:15-crown-5; D008049:Lipase