Serendipitous synthesis of 3-hydroxy tetrahydrofurans from tin catalyzed sulfonylation of acyclic 1,2,4-triols |
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Authors: | Makhosazana P GamedzeRejoice B Maseko Fidelis ChigondoComfort M Nkambule |
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Institution: | Department of Chemistry, Tshwane University of Technology, Private Bag X680, Pretoria 0001, South Africa |
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Abstract: | The reaction of syn-1,2,4-triols under sulfonylation conditions catalyzed by Bu2SnO (5 mol %) results in cyclization and the formation of 3-hydroxy tetrahydrofurans (56-85%) while the anti-1,2,4-triols react to give C1-O-sulfonyl derivatives in good yields (66-83%) and the cyclization product in poor yield (5-12%). A mechanism that justifies these observations is proposed to occur via the tosylation of the primary hydroxyl followed by an intramolecular tin acetal rearrangement to a 1,3-stannylene which then undergoes a 5-exo-tet-cyclization. The difference in rates of cyclization reactivity is due to the energetically more stable tin acetals of syn-1,3-diols compared to those of anti-1,3-diols. |
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Keywords: | Sulfonylation Tin acetal 1 2 4-Triols 1 3-Diols Tetrahydrofurans |
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