Xiang-Guo Li, Maria Lähitie, Mari Päiviö
Jul 17, 2007
Citations
2
Influential Citations
26
Citations
Journal
Tetrahedron-asymmetry
Abstract
Abstract This paper concentrates on studies of the acylation of alcohols with 3,3-difluoro-4-phenylazetidin-2-one rac - 1 , trans -3-fluoro-4-phenylazetidin-2-one rac - 2 and 4-phenylazetidin-2-one rac - 3 in the presence of immobilized lipase PS from Burkholderia cepacia in dry tert -butyl methyl ether (TBME). Fluorine activation in the compounds studied was essential in order to split the β-lactam ring with lipase PS. The highly enantioselective ring opening of rac - 1 and rac - 2 with methanol (1-butanol was also studied) allowed the preparation of the ( R /(3 R ,4 R ))-β-lactams as the unreacted enantiomers and ( S /(2 S ,3 S ))-β-amino esters as the product enantiomers with an ee >99%. Under the same conditions, rac - 3 was totally unreactive. The possibility for a competing hydrolysis caused by water in the enzyme preparations is also discussed.