효소-금속 촉매를 혼용한 1,2-Diarylethanols의 동적 속도론적 광학 분할

• Main Author: 김솔
• Other Authors: 일반대학원 화학과, 포항공과대학교
• Format: Thesis
• Language: English
• Published: 포항공과대학교 2013
• Subjects: Antarc*; Antarctica
• Online Access: http://postech.dcollection.net/jsp/common/DcLoOrgPer.jsp?sItemId=000001557732; https://oasis.postech.ac.kr/handle/2014.oak/1803

Doctor Dynamic kinetic resolution (DKR) provides a practical method for the conversion of racemic substrates to single enantiomeric products. In the last decade, Kim and Park’s group and others have developed various DKR systems consist of enzymes and metals. For example, the DKR of a wide range of racemic secondary alcohols can be achieved with a lipase-ruthenium combination. Ruthenium complexes are used as a racemization catalyst in DKR and have been remarkably improved by some leading groups including ours. On the other hand, the use of enzymes is relatively limited that only a few enzymes have been practically introduced to DKR. Particularly, enzymes generally fail to resolve secondary alcohols possessing two similar-in-size substituents at the hydroxymethine center. The objective of this work thus was to develop the practical procedures for the DKR of sterically demanding secondary alcohols using enzyme-metal combination.I have investigated the enzymatic kinetic resolution (EKR) of seventeen 1,2-diarylethanols as sterically demanding secondary alcohols. It was found that all of them were accepted by PSL with high enantioselectivities. Addition of inorganic base such as potassium phosphate or potassium carbonate increased the activity of PSL but also caused a chemical acylation reaction. The racemization of chiral 1,2-diarylethanols was successfully completed by ruthenium complex. I conducted the DKR of 1,2-diarylethanols using PSL and ruthenium catalyst to obtain optically pure 1-acetoxy-1,2-diarylethanols. The DKR reactions were performed with solutions containing substrate (0.2 mmol), ruthenium catalyst (8 mol%), PSL (120 mg / mmol), isopropenyl acetate (1.5 equiv), and K2CO3 (1 equiv) in toluene at 25 oC. All of 1,2-diarylethanols were successfully transformed into their acetates with high yields (95-99%) and excellent enantiopurities (96-99%).I also have explored the (S)-selective DKR of 1,2-diarylethanols. First, I examined the EKR of 1-phenyl-2-arylethanols by Candida antarctica lipase A (CALA). ...