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Synthesis of 2-heteroaryl substituted chiral fused cyclopenta[c]pyridine derivatives via pauson-khand reaction

Gümrükçü, Yasemin
The racemic homoallylic and homopropargylic alcohol derivatives were resolved by applying chemoenzymatic method using various lipase type enzymes i.e., PS-C II, Lipozyme, CAL-B. The enantiomeric excess values of the resultant alcohols were determined by HPLC. These enantiomerically enriched homoallylic and homopropargylic alcohols were subjected to N-propargylation and N-allylation, respectively, by SN2 and modified Mitsunobu reactions. During the course of all reactions, stereochemistry of the chiral centers were under controlling according to the known reaction mechanisms. The resultant chiral N-tosylated enyne derivatives afforded the corresponding chiral fused cyclopenta[c]pyridinone derivatives (69, 73, 75 and 77) with acceptable chemical yields and excellent diastereoslectivity depending upon the conformational effect on the complete remote stereochemical control for the newly generated chiral centers. The chemoenzymatic applications done with biocatalysis (lipases) and the Pauson-Khand reaction are involved in “Green Chemistry” approach.