RESUMO
Dynamic kinetic asymmetric transformation (DYKAT) of 1,5-diols via combined lipase and ruthenium catalysis provides enantiomerically pure diacetates in high diastereoselectivity, which can serve as intermediates in natural product synthesis. This is demonstrated by the synthesis of (+)-Solenopsin A.
Assuntos
Álcoois/química , Alcaloides/síntese química , Lipase/metabolismo , Rutênio/química , Alcaloides/química , Catálise , Cinética , Lipase/química , Estrutura Molecular , EstereoisomerismoRESUMO
Dynamic kinetic asymmetric transformation (DYKAT) of a series of 1,5-diols has been performed in the presence of Candida antarctica lipase B (CALB), Pseudomonas cepacia lipase II (PS-C II), and ruthenium catalyst 4. The resulting optically pure 1,5-diacetates are useful synthetic intermediates, which was demonstrated by the syntheses of both an enantiopure 2,6-disubstituted piperidine and an enantiopure 3,5-disubstituted morpholine.
Assuntos
Álcoois/química , Compostos Heterocíclicos/síntese química , Burkholderia cepacia/enzimologia , Catálise , Proteínas Fúngicas , Compostos Heterocíclicos/química , Cinética , Lipase/química , Estrutura Molecular , Rutênio/química , EstereoisomerismoRESUMO
A number of 1,3-cycloalkanediones were efficiently reduced to the corresponding diols in good yield by the use of a ruthenium catalyst, 2-propanol, and hydrogen gas under microwave heating.
Assuntos
2-Propanol/química , Alcanos/química , Cicloparafinas/química , Micro-Ondas , Rutênio/química , Catálise , Ciclização , Temperatura Alta , Hidrogenação/efeitos da radiação , Estrutura Molecular , OxirreduçãoRESUMO
An efficient desymmetrization of cis-1,3-cyclohexanediol to (1S,3R)-3-(acetoxy)-1-cyclohexanol ((R,S)-2a) was performed via Candida antarctica lipase B (CALB)-catalyzed transesterification, in high yield (up to 93%) and excellent enantioselectivity (ee's up to >99.5%). (R,R)-Diacetate ((R,R)-3a) was obtained in a DYKAT process at room temperature from (1S,3R)-3-acetoxy-1-cyclohexanol ((R,S)-2a), in a high trans/cis ratio (91:9) and in excellent enantioselectivity of >99%. Metal- and enzyme-catalyzed dynamic transformation of cis/trans-1,3-cyclohexanediol using PS-C gave a high diastereoselectivity for cis-diacetate (cis/trans = 97:3). The (1R,3S)-3-acetoxy-1-cyclohexanol (ent-(R,S)-2a) was obtained from cis-diacetate by CALB-catalyzed hydrolysis in an excellent yield (97%) and selectivity (>99% ee). By deuterium labeling it was shown that intramolecular acyl migration does not occur in the transformation of cis-monoacetate to the cis-diacetate.
