Synthesis of dibenz[b,f]oxepins via manganese(III)-based oxidative 1,2-radical rearrangement.

ABSTRACT

The oxidation of monoalkyl 2-(9H-xanthenyl)malonates 1 with Mn(OAc)(3) gave the 9- or 10-dibenz[b,f]oxepincarboxylates 2 in good yields. The reaction proceeds with high regioselectivity except for the case of (1-methoxyxanthenyl)malonate 1 (R(1) = Me, R(2) = 1-MeO), which gave two regioisomers. It was proposed that the process for the formation of 2 must include the 1,2-aryl radical rearrangement followed by oxidative decarboxylation.