Nucleophilic substitution at the anomeric position of 1,2-O-isopropylidenefuranose derivatives. A novel stereoselective synthesis of cyclic phosphates analogous to cAMP |
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Authors: | Romero Miriam Hernández Luís Quintero Leticia Sartillo-Piscil Fernando |
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Affiliation: | Centro de Investigación de la Facultad de Ciencias Químicas, Benemérita Universidad Autónoma de Puebla, 14 Sur Esq. San Claudio, Col. San Manuel, 72570 Puebla, Mexico. |
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Abstract: | 1,2-O-Isopropylidenefuranose derivatives were treated with various nucleophiles in the presence of either BF(3).OEt(2) or trimethylsilyl trifluoromethanesulfonate (TMSOTf) leading to substitution products in a regio- and stereoselective manner. In particular, nucleophilic substitution of 1,2-O-isopropylidenefuranose derivatives when treated with allyltrimethylsilane was controlled by steric and electronic factors (similar to Woerpel's stereoelectronic model). On the other hand, when 1,2-O-isopropylidenefuranose derivatives were treated with trimethylsilane, in the presence of bis-O-trimethylsilyl-5-iodouracil or bis-O-trimethylsilyl-thymidine, substitution products were generated in high regio- and stereoselectivities via an unusual nucleophilic substitution with opening of the furanose ring. Based on these results, a stereoselective method for the synthesis of neutral cyclic phosphates analogous to cAMP was developed. |
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Keywords: | Nucleosides Analogous cAMP Nucleophilic substitution Oxacarbenium |
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