Date of Award:
Master of Science (MS)
Chemistry and Biochemistry
Richard K. Olsen
Three different synthetic approaches toward N-[(2SR, 4S)-4-hydroxy-2,5-dimethyl-3-oxohexanoyl]-Lleucine methyl esters were carried out by use of i) aldol condensation and amination ii) Claisen condensation and soft acid coupling reaction iii) methylation of Hia-Leu derivative in relatively high yields. (4S)-3-[(2SR,4S)-2,5-Dimethyl-1,3-dioxo-4-(methoxyethoxymethyloxy) hexyl]-4-(1-methylethyl)-2-oxazolidinone was prepared by the reaction of aldol condensation of lithium enolate of Evans' chiral auxilary in 80 : 20 diastereomeric ratio. A new method for the synthesis of (4S)-4-(t-butoxycarbonyl)amino-5-methyl-3- oxoheptanoic acid ethyl ester (Statone) was developed by the reaction of Boc-leucine with Meldrum's acid, followed by transesterification and decarboxylation in modest yield. Other a-amino acids also were applied to this methodology in successful yields. Attempts to prepare the linear molecule, containing Statone-(4S)-5-methyl- 3-oxohexanoyl- Leu-OCpa, an analogue of Epista-Hip-Leu, was not successful.
Kim, Ok-Soon, "Synthetic Studies Toward Key Portions of the Didemnins" (1988). All Graduate Theses and Dissertations. 7212.
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