Development and Application ofEnzymatic Asymmetric Synthesis ofFunctionalized Alcohols
2015 (English)Licentiate thesis, comprehensive summary (Other academic)
The main focus of this thesis lies on enzymatic asymmetric organic reactions. In the first part ofthis work, we looked into the lipase-catalyzed transesterification and hydrolysis at the molecularlevel. It was shown that the low enantioselectivity of CALB-catalyzed transesterification of a δ-functionalized alkan-2-ol to its acetate does not correlate at all with the high enantioselectivity ofthe CALB-catalyzed hydrolysis of the corresponding acetate in water. This lack of correlation isunusual and for unfunctionalized alkan-2-ol derivatives there is a very good correlation betweenthe enantioselectivity of transesterification of the alcohol and hydrolysis of the correspondingacetate with a high enantioseletivity in both cases. The results confirm previous predictions frommolecular modeling. The water effect was mimicked by CALB variant Ala281Ser, whichshowed an enhanced enantioselectivity in transesterification of δ-functionalized alkan-2-olscompared to wild type CALB.
In the second part of the thesis, enzymatic kinetic resolution to resolve 1-substituted buta-2,3-dien-1-ol was studied. The initial goal was to use Shvo catalyst as racemization catalyst for anenvisioned dynamic kinetic resolution of this substrate. To our surprise, 2,3-dihydrofurans wasformed when α-allenic alcohols was treated with Shvo catalyst and the chiral center that endedup in the product was unchanged. Based on the KR and cycloisomerization, we furthermoredeveloped a one-pot procedure combining kinetic resolution and cyclization to optically pureoxygen-containing heterocycles. The mechanism of the Ru-catalyzed cycloisomerization wasstudied and a Ru-carbenoid was suggested as a crucial intermediate for forming the 2,3-dihydrofurans.
Place, publisher, year, edition, pages
Stockholm: Stockholms universitets förlag, 2015. , 36 p.
Natural Sciences Chemical Sciences
IdentifiersURN: urn:nbn:se:su:diva-124400OAI: oai:DiVA.org:su-124400DiVA: diva2:885832