Serendipitous synthesis of 3-hydroxy tetrahydrofurans from tin catalyzed sulfonylation of acyclic 1,2,4-triols
作者:Makhosazana P. Gamedze、Rejoice B. Maseko、Fidelis Chigondo、Comfort M. Nkambule
DOI:10.1016/j.tetlet.2012.08.110
日期:2012.10
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. (C) 2012 Elsevier Ltd. All rights reserved.