Stereoselective construction of spiroacetal framework and evaluation of its thermodynamic/kinetic stability

摘要

A spiroacetal is bicyclic acetal composed of two acetal bonds between spiro-carbon and oxygen atoms in different rings. This motif usually possesses the chiral spiroacetal carbon, and is often seen in biologically active natural products.1,2 The kinetics information would let us to properly handle the spiroacetal compounds to avoid the undesired isomerization. However, it has not been fully explored except for some studies of spiroacetal isomerization under harsh (e.g. acidic-, or thermal-) conditions.3,4 One of the main reason is the lack of a general method to systematically synthesize unstable isomers, which are necessary for detailed kinetic evaluation.