Synthesis of anellated carbasugars from (--)-quinic acid |
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Authors: | Herrera Lidcay Feist Holger Michalik Manfred Quincoces José Peseke Klaus |
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Affiliation: | Fachbereich Chemie, Universit?t Rostock, D-18051, Rostock, Germany. |
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Abstract: | (3R,4R,5R)-3-[(tert-Butyl-dimethylsilyl)oxy]-4,5-(isopropylidenedioxy)-1-cyclohexanone (2) reacted with carbon disulfide and methyl iodide in the presence of sodium hydride to furnish (3R,4R,5R)-5-[(tert-butyl-dimethylsilyl)oxy]-3,4-(isopropylidenedioxy)-2-[bis(methylthio)methylene]-1-cyclohexanone (3). 2 and N,N-dimethylformamide dimethyl acetal afforded (2E,3R,4R,5R)-5-[(tert-butyl-dimethylsilyl)oxy]-2-(dimethylaminomethylene)-3,4-(isopropylidenedioxy)-1-cyclohexanone (4). These push-pull activated methylenecyclohexanones 3 and 4 underwent a ring closure reaction with hydrazine hydrate and methylhydrazine, respectively, to give pyrazoloanellated carbasugars. Treatment of 3 with formamidinium, acetamidinium and benzamidinium salts, respectively, in the presence of sodium methanolate yielded three (5R,6R,7R)-7-[(tert-butyl-dimethylsilyl)oxy]-5,6,7,8-tetrahydro-5,6-(isopropylidenedioxy)benzo[d]pyrimidines. |
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Keywords: | (−)-Quinic acid Benzo[c]pyrazoles Benzo[d]pyrimidines, α-Oxoketene-S,S-acetals Push-pull alkenes |
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