A new method for the synthesis of carba-sugar enones (gabosines) using a mercury(II)-mediated opening of 4,5-cyclopropanated pyranosides as the key-step |
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Authors: | Antonino Corsaro Venerando Pistarà Felicia D’Andrea Maria Assunta Chiacchio |
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Institution: | a Dipartimento di Scienze Chimiche, Università degli Studi di Catania, viale A. Doria 6, Catania 95125, Italy b Dipartimento di Chimica Bioorganica e Biofarmacia, Università degli Studi di Pisa, via Bonanno 33, Pisa 56126, Italy |
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Abstract: | The stereoselective transformation of the cyclopropyl derivative 2, stereoselectively obtained with the Simmons-Smith reaction of methyl 2,6-di-O-benzyl-α-l-threo-hex-4-enopyranoside (1), into gabosines and deoxy-carbahexoses is described. The treatment of 2 with mercuric trifluoroacetate in dry methanol gives the organomercuric chloride 3, which by demercuration with lithium aluminum hydride affords the 4-C-deoxy-4-methyl-1,5-bis-glycoside 4. The acid hydrolysis of 4 produces a mixture of the two diastereoisomeric 2-methyl-cyclohex-2-enones 6 and 7, catalytically reduced to carba-sugars 10 and 11. Structures and stereochemistry of all isolated compounds were determined by 1D and 2D NMR experiments. |
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Keywords: | 4 5-Cyclopropanated sugars Intramolecular aldol condensation Gabosines 6-Deoxy-5a-carba-hexopyranosides |
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