Synthesis of optically active 3-substituted-10-alkyl-10H-phenothiazine-5-oxides by enantioselective biotransformations
摘要:
A series of racemic 10-alkyl-3-formyl-10H-phenothiazine-5-oxides (+/-)-2a-h were subjected to biotransformation with baker's yeast resulting in optically active aldehydes (+)-2a-h and alcohols (-)-3a-h in moderate enantiomeric excess. The racemic 10-alkyl-3-hydroxymethyl-10H-phenothiazine-5-oxides (+/-)-3a-h and 3-acetoxymethyl-10-alkyl-10H-phenothiazine-5-oxides (+/-)-4a-h obtained from the racemic aldehydes ()-2a-h were also tested in enantioselective lipase-catalyzed acetylations and alcoholysis reactions. The highest enantiomeric purities were achieved by a Novozyme 435-catalyzed acetylation-ethanolysis sequence, leading to optically active alcohols (-)-3a h in 83-92% e.e. A novel NMR method using enantiopure dibenzoyl tartaric acid as chiral additive was developed for determination of the enantiomeric composition of the optically active products. (C) 2002 Elsevier Science Ltd. All rights reserved.
Synthesis of optically active 3-substituted-10-alkyl-10H-phenothiazine-5-oxides by enantioselective biotransformations
摘要:
A series of racemic 10-alkyl-3-formyl-10H-phenothiazine-5-oxides (+/-)-2a-h were subjected to biotransformation with baker's yeast resulting in optically active aldehydes (+)-2a-h and alcohols (-)-3a-h in moderate enantiomeric excess. The racemic 10-alkyl-3-hydroxymethyl-10H-phenothiazine-5-oxides (+/-)-3a-h and 3-acetoxymethyl-10-alkyl-10H-phenothiazine-5-oxides (+/-)-4a-h obtained from the racemic aldehydes ()-2a-h were also tested in enantioselective lipase-catalyzed acetylations and alcoholysis reactions. The highest enantiomeric purities were achieved by a Novozyme 435-catalyzed acetylation-ethanolysis sequence, leading to optically active alcohols (-)-3a h in 83-92% e.e. A novel NMR method using enantiopure dibenzoyl tartaric acid as chiral additive was developed for determination of the enantiomeric composition of the optically active products. (C) 2002 Elsevier Science Ltd. All rights reserved.
A series of racemic 10-alkyl-3-formyl-10H-phenothiazine-5-oxides (+/-)-2a-h were subjected to biotransformation with baker's yeast resulting in optically active aldehydes (+)-2a-h and alcohols (-)-3a-h in moderate enantiomeric excess. The racemic 10-alkyl-3-hydroxymethyl-10H-phenothiazine-5-oxides (+/-)-3a-h and 3-acetoxymethyl-10-alkyl-10H-phenothiazine-5-oxides (+/-)-4a-h obtained from the racemic aldehydes ()-2a-h were also tested in enantioselective lipase-catalyzed acetylations and alcoholysis reactions. The highest enantiomeric purities were achieved by a Novozyme 435-catalyzed acetylation-ethanolysis sequence, leading to optically active alcohols (-)-3a h in 83-92% e.e. A novel NMR method using enantiopure dibenzoyl tartaric acid as chiral additive was developed for determination of the enantiomeric composition of the optically active products. (C) 2002 Elsevier Science Ltd. All rights reserved.