An oxidant dependent switchable palladium-catalyzed synthesis
of
1,3-oxazines and benzohydrazonates (azines) from O-homoallyl benzimidates has been developed. The reaction involved
aza-Wacker-type intramolecular cyclization of O-homoallyl
benzimidates with Cu(OAc)2 as oxidant under Pd-catalysis
to deliver 4-methylene-1,3-oxazines, whereas dimerization of O-homoallyl benzimidates with K2S2O8 as oxidant resulted remarkably in benzohydrazonates
(azines). The reaction is atom economic with an easily operational
procedure for divergent synthesis of important scaffolds.