Synthesis and stereochemistry of indano1,2d1,3oxazines and thiazines, new ring systems

A set of structurally varied indano1,2d1,3oxazines and thiazines, which are new ring systems, were prepared by ringclosure reactions of amino alcohols 4–6. The reactions of cis and trans1amino and cis 1benzylamino2hydroxymethylindane 4–6 with 1 equivalent of an aromatic aldehyde in methanol at room temperature resulted in threecomponent equilibria 15ag, or a Schiff base 16, or a ringclosure product alone 17ac, respectively, depending on the substitution or configuration of the starting amino alcohol. The ringchain tautomeric equilibria can be described by an equation of Hammett type.