| abstract |
An azaindoline spiro-oxazine of the general formula (I): ##STR1## wherein R 1 represents an aliphatic or aromatic group; each of R 2 and R 3 independently represents a hydrogen atom, an aliphatic or aromatic group or an alkoxy group, or R 2 and R 3 together with the carbon atom to which they are attached represent an alicyclic group; n R 4 represents a hydrogen atom or an aliphatic or aromatic group; n ring A contains one or more nitrogen atoms in the ring and may be unsubstituted or substituted provided that there is no substituent on any nitrogen atom in the ring; and n ring B may be unsubstituted or substituted by at least one substituent provided that the 6'-position in ring B is not substituted by an amine function or hydroxyl group. The spiro-oxazine compounds are useful for imparting photochromic properties to a plastics host material such as a plastics lens. |