Synthesis of 3,4-fused y-lactone-y-lactam and y-lactonepyrrolidine bicyclic systems / Nur Aini Azib
In this study, bicyclic moieties 3,4-fused y-lactone-y-lactam and y-lactone-pyrrolidine were chosen as the target molecules due to their highly functionalized structures and their ability to be bioactive 5,5-bicyclic molecules. The synthetic strategy was divided into three main parts in which the fi...
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| Format: | Book Section |
| Language: | English |
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Institute of Graduate Studies, UiTM
2018
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| Online Access: | http://ir.uitm.edu.my/id/eprint/22027/ http://ir.uitm.edu.my/id/eprint/22027/1/ABS_NUR%20AINI%20AZIB%20TDRA%20VOL%2014%20IGS%2018.pdf |
| Summary: | In this study, bicyclic moieties 3,4-fused y-lactone-y-lactam and y-lactone-pyrrolidine were chosen as the target molecules due to their highly functionalized structures and their ability to be bioactive 5,5-bicyclic molecules. The synthetic strategy was divided into three main parts in which the first part concentrated on the construction of the key-intermediates, lactam and pyrrolidine ring moieties, from D-alanine methyl ester hydrochloride. The approach involved N-protection of the starting material with either benzyl or Boc protecting groups. Condensation with methyl malonyl chloride followed by Dieckmann cyclization gave the required y-lactam ring moiety 5 which is also known as the p,pdiketoester with an overall yield of 39%. Consequently, decarboxylation of the methyl ester functional group followed by reduction of the keto amide functionality with LiAlH4 afforded the desired pyrrolidine ring 25 in 18% overall yield. The second part focused on the formation of the fused y-lactone-y-lactam and y-lactone-pyrrolidine bicyclic systems. The y-lactam ring moiety underwent C-alkylation reaction at the C3-position via insertion of the ethyl acetyl functionality by utilizing TBAF as the base. Subsequently, selective dimethoxy-carbonylation was performed using two different decarboxylating agents which were a salt-solvent system, Lil/DMF, and an acid medium, HCl/AcOH; both successfully gave decarboxylated products but the former with the presence of C-3 methyl group as anticipated and the latter without… |
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