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DOI: 10.1055/s-1992-26248
Synthesis of Dihydroxyethylene Isosteres of Dipeptides; 2. Isosteres of Leu-Ala and Leu-Val from Suitably Substituted 3-Dimethylphenylsilyl-4-octanolides
Publikationsverlauf
Publikationsdatum:
17. September 2002 (online)
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Homochiral 2-alkyl-5-amino-3-hydroxy-5-octanolides 4a,b, 5b, 6b and 9a, representing protected ψ [CHOHCHOH] dipeptides, were prepared by stereospecific oxydesilylation of the appropriate 3-dimethylphenylsilyl derivatives, 1a-c and 7a. Alternatively, anti-selective Peterson elimination of the diastereomeric 3,4-trans-substituted γ-lactones 1a or 1b followed by esterification yielded methyl (2R,3E,5S)-5-(tert-butoxycarbonylamino)-2, 7-dimethyl-3-octenoate (14a), which on syn-bishydroxylation led to the 2R,3S,4S,5S- and 2R,3R,4R,5S-stereoisomers of ψ [CHOHCHOH]-L-leu-L-ala, 17a and 18a. In combination with the results of the preceding paper, a general procedure is outlined for the rapid synthesis of various diasteromers of dipeptide dihydroxyethylene isosteres.