Pd(II)-catalyzed oxidative intramolecular cyclizations by C-O bond formation for the synthesis of 1,4-oxazine derivatives

The prominent role of Pd(II) catalysis for the formation of C-O bond by using unsaturated hydrocarbon substrates has been well documented.1 The substrates envisioned for this work consisted of a suitable tools for the intramolecular version of this strategy with the formation of 1,4-oxazine rings. When the N-allyl N-hydroxyethyl amides A were treated with O2 as sole oxidant, the alkoxylation reaction gave dihydrooxazines B. Following different reaction conditions, hydroalkoxylation process was observed providing morpholine derivatives C, depending on the nature of the nucleophilic reagents. The substrates were treated also in carbonilative conditions, giving the carbomethoxy derivatives.