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The the natural ring ester the peptide Obyanamide the synthesis of human tumor cells KB and LoVo moderate cytotoxic natural products Obyanamide is the first time in 2002 , near the University of Hawaii , Moore RE inhabit the waters of Spain Mariana Saipan the cyanobacteria Lyngbya confervoides and 19 - membered cyclic ester isolated peptide . The structural characteristics of the compound , the use of anti - synthetic design , this article will be cut into four synthetic fragment : fragment A ( N-methyl- valine -N-methyl phenylalanine dipeptide ) , fragment B ( thiazol- acid derivative), fragment C (L- lactic acid derivative ) and fragment D ( β - aminovaleric acid derivative) , and each of the synthetic fragment were synthesized , the final completion of the total synthesis of the target compound Obyanamide . Fragment A synthesis : as raw material to the L-phenylalanine and L-valine , tert-butyl , o - nitrobenzenesulfonyl chloride protection , methylation, and deprotection , acylation , the coupling step reaction smoothly Synthesis of N- methyl - dipeptide having a larger steric structural fragment a , yield 48.2% . fragment B Synthesis of : L-alanine and L-serine as the raw material, by Boc protection, esterification , coupling , TBS protected vulcanized de TBS protected dehydration cyclization , oxidation, ester hydrolysis, esterification, and deprotection of ten steps synthesis of chiral thiazole derivative fragment B , a yield of 14.8 % ee value is greater than 98% of fragment C synthesis : L-lactic acid as the raw material, its intramolecular hydroxy with oxalyl chloride in DMF catalytic esterification reaction of the fragment C , yield 98% . fragment D Synthesis : (S) -2 - amino butyric acid as the starting material the Boc protected diazotization Wolff rearrangement , methyl ester hydrolysis reaction of β- amino acid fragment D , a yield of 84.8 % . lt ; WP = gt ; the coupling reaction between the fragments : fragment A de - protection of o-NBS condensed with fragment C , and the resulting compound through the de- protection , coupling and Fragment B , desacetyl protected with fragment D esterification , deprotection , and finally coupling reagent the FDPP the catalyst the intramolecular cyclization natural cyclic ester peptide Obyanamide. overall yield was 3% ( phenylalanine ) .
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