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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Synthetic Studies Toward Key Portions of the Didemnins

Kim, Ok-Soon 01 May 1988 (has links)
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.

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