- Use of heterocycles as chiral ligands and auxiliaries in asymmetric syntheses of sphingosine, sphingofungins B and F
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D-erythro-Sphingosine and its derivatives (dihydrosphingosine, cissphingosine, etc.), sphingofungins B and F have been synthesized from simple achiral compounds using heterocyclic compounds as key chiral ligands and auxiliaries. 5-Benzyloxy-4-ethynyl-2,2-dimethyl-1,3-dioxane (5 or 5- ent), a key intermediate for the synthesis of sphingosine family, was prepared from 1-trimethylsilylpropinal and ketene silyl acetal 4 using a Sn(OTf)2-chiral ligand 1 or 1-ent-catalyzed asymmetric aldol reaction. Sphingosine and its derivatives were readily prepared from 5 according to standard transformation. The chiral hydrophobic side chain (6) of sphingofungin B was synthesized using a catalytic asymmetric aldol reaction using chiral ligand 1-ent. Another key step in the total synthesis of sphingofungin B was a condensation of chiral aldehyde 7 and chiral heterocycle 2. Similarly, the reaction of chiral aldehyde 8 with heterocycle 3 was a key step for the synthesis of sphingofungin F. Highly diastereoselective reactions proceeded smoothly in both cases to afford the corresponding adducts in high yields.
- Kobayashi, Shu,Furuta, Takayuki
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p. 10275 - 10294
(2007/10/03)
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- Catalytic asymmetric syntheses of antifungal sphingofungins and their biological activity as potent inhibitors of serine palmitoyltransferase (SPT)
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Unambiguous synthetic routes to sphingofungins B and F and to their stereoisomers have been developed based on the tin(II)-catalyzed asymmetric aldol reaction (Chiral Lewis Acid-Controlled Synthesis (CLAC Synthesis)). Efficient enantioselective synthesis using a catalytic amount of a chiral source as well as the effectiveness of this strategy for the synthesis of the sphingofungin family have been successfully demonstrated. Using the stereoisomers of sphingofungin B synthesized, the relevance of its stereochemistry to its SPT inhibitory activity has been revealed.
- Kobayashi, Shu
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p. 908 - 919
(2007/10/03)
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- The Asymmetric Synthesis of Sphingofungin F and the Determination of Its Stereochemistry
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The asymmetric synthesis of sphingofungin F has been achieved and its stereochemistry has been determined. Its structure, including the absolute configuration of the chiral centers, was found to be similar to that of sphingofungin B or myriocin. The synth
- Kobayashi, Sh?,Matsumura, Masae,Furuta, Takayuki,Hayashi, Takaomi,Iwamoto, Shunsuke
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p. 301 - 303
(2007/10/03)
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