- Total synthesis of pipecolic acid and 1-: C -alkyl 1,5-iminopentitol derivatives by way of stereoselective aldol reactions from (S)-isoserinal
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A short synthesis of iminosugars and pipecolic acid derivatives has been realized through aldol addition of a pyruvate, a range of ketones and (S)-isoserinal, followed by catalytic reductive intramolecular amination. The stereoselective aldol reaction was achieved successfully by using tertiary amines or di-zinc aldol catalysts, thus constituting two parallel routes to optically pure products with good yields and high diastereo-selectivities. These carbohydrate analogues may be the inhibitors of potent glycosidases and glycosyltransferases.
- Ba?, Sebastian,Kusy, Rafa?,Pasternak-Suder, Monika,Nicolas, Cyril,Mlynarski, Jacek,Martin, Olivier R.
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p. 1118 - 1125
(2018/02/21)
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- Organocatalytic syn-aldol reactions of hydroxy ketones with (S)-isoserinal: Asymmetric synthesis of 6-deoxy-1,5-iminohexitols and related compounds
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An improved and convenient preparation of protected (S)-isoserinal on a large scale is reported. This key intermediate was reacted through organocatalyzed aldol reaction or Wittig based chain extension and functionalization to give enantiopure 1,5,6-trideoxy-1,5-imino-hexitols such as 10a (L-manno) and 10b (D-gluco). These two compounds are of interest as glycosidase inhibitors. The elaborated organocatalytic process includes diastereoselective syn aldol reaction of (S)-isoserinal hydrate and hydroxyacetone or 1-hydroxy-2-octanone and is promoted by various amino acid-based catalysts. Diastereoselectivities of up to 8:1 were achieved, thus establishing a new, efficient synthetic route to these important carbohydrate mimics. A novel protocol for the preparation of 1,5,6-trideoxy-1,5-imino-L- mannitol and 1,5,6-trideoxy-1,5-imino-D-glucitol is reported. The key steps include organocatalyzed syn-selective direct aldol reaction of hydroxyacetone and CBz-protected isoserinal hydrate, followed by reductive amination/ cyclization. Copyright
- Nicolas, Cyril,Pluta, Roman,Pasternak-Suder, Monika,Martin, Olivier R.,Mlynarski, Jacek
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p. 1296 - 1305
(2013/04/10)
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