A carbanion induced ring switching synthesis of spiranes an unprecedented approach

Hardesh K. Maurya ,  Ramendra Pratap ,  Abhinav Kumar ,  Brijesh Kumar ,  Volker Huch ,  Vishnu K. Tandon and Vishnu Ji Ram

RSC Adv., 2012,2, 9091-9099

                                                                                                                                           
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DOI: 10.1039/C2RA21587J

An unique approach to the synthesis of heterocyclic spiranes through ring switching transformation of suitably functionalized 2H-pyran-2-ones, benzo[h]chromene and thiochromeno[4,3-b]pyrans has been developed. The spirane dimer 11d displayed interestinghalogen-hydrogen bonding to generate an elliptical cavity and may be relevant to the generation of a host guest assembly for specific cations and also a low helimerization energy barrier of spirane 17a.