A synthetic entry into the 2‐ and 3‐substituted‐methyl 2,3‐dihydro‐1,4‐benzoxazine series

Nmr spectroscopy has been used to demonstrate that the reported preparation of supposed 3‐bromomethyl‐2,3‐dihydro‐1,4‐benzoxazine (3) is in error, the product of the reaction being in reality a monocyclic compound, 4. An alternative entry to the 3‐substituted series is described in the synthesis of the 3‐hydroxymethyl derivative, 10, the structure of which was established by nmr and mass spectroscopy. The previous assignment of structure to 2‐carbethoxy‐2,3‐dihydro‐1,4‐benzoxazine, prepared by an ambiguous route, and to compounds derived from this ester, is shown to be correct.