6 Didemniserinolipid Bの全合成と構造の改定(口頭発表の部)

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Synthesis of two possible diastereomers of (+)-didemniserinolipid B (1), the first natural serinolipid isolated from a tunicate Didemnum sp., were studied. The known butanediacetal (BDA) protected aldehyde 2 was converted to the core coupling component 8. The serinol fragments (S)-13 and (R)-13 were prepared from D-serine and L-serine, respectively. Wittig-Horner reaction of 8 and (S)-13 gave (4"S)-14, which was converted to ester (4"S)-18. Finally, removal of all the protecting group was achieved in acidic EtOH to afford (30S)-1. Similarly, (30R)-1 was synthesized from (R)-13. However, the ^1H and ^<13>C NMR spectra of the synthetic 1 were different from those of natural 1. In view of the fact that related natural products were sulfated on the serinol unit we therefore believed the 31 position of the natural 1 should be sulfated. Based on this assumption, we investigated further derivatization of the synthetic compounds. We studied sulfation of N-Fmoc derivative (30R)-19, however, with the usual reagents and conditions resulted in only recovery of the starting material. Finally we developed new microwave-assisted sulfation conditions which gave the desired monosulfate, followed by the Fmoc deprotection affording 31-monosulfate (30R)-20. As the ^1H and ^<13>C NMR data and the value of the specific optical rotation of (30R)-20 coincided with those of the natural product, we concluded that the real structure of (+)-didemniserinolipid B corresponded to a 31-sulfate and the absolute configuration was 8R,9R,10R,13S,30S. The microwave-assisted sulfation developed in this process are effective for unreactive hydroxyl groups.
天然有機化合物討論会の論文
2002-09-01

6 Didemniserinolipid Bの全合成と構造の改定(口頭発表の部)

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