Initial studies were based on previous work at Edinburgh in which the reaction of the lithium salt of 1,2-naphthalenedione 1-oxime with 2-bromo-2,2-diphenylacetaldehyde was found to afford an oxime ether which was reduced with triphenylphosphine to afford 3,3-diphenyl-3H-naphth[2,1-b]-1, 4-oxazine. Similarly, 2,2-diphenyl-2H-naphth[1,2-b]-1,4-oxazine was prepared in a parallel synthetic strategy using 1,2-naphthalenedione 2-oxime as key starting material. To facilitate the expansion of this strategy, further bromo-aldehydes functionalised with variously substituted aromatic moieties were prepared. Reaction of these bromo-aldehydes with 1,2-naphthalenedione 1-oxime lithium salt, followed by reduction of the resulting oxime ethers, facilitated the synthesis of a number of novel 3,3-diaryl-3H-naphth[2,1-b]-1,4-oxazine derivatives. On encountering problems in the synthesis of certain diaryl bromo-aldehydes, the synthesis of alternative diarylacetaldehyde derivatives amenable to reaction with naphthalenedione oxime lithium salts was previously inaccessible halogeno-aldehydes was investigated. Using 1,2-naphthalenedione 2-oxime and 9, 10-phenanthrenedione 9-oxime as starting materials the aforementioned methodologies were applied to the respective syntheses of 2,2-diaryl-2H -naphth[1,2-b]-1,4-oxazines and 2,2-diaryl-2H-phenanthro[9,10-b]-1,4-oxazines. Investigations were also made into the mechanism of the formation of these novel photochromic species. The chemistry of certain novel naphth-1, 4-oxazines and phenanthro-1, 4-oxazines was investigated and they were found to behave as cyclic imines. Photochromic 3,3-diaryl-3H-pyrido[3,2-f]-1, 4-benzoxazines were also prepared. However, the attempted synthesis of 2,2-diphenyl-2H-acenaphtho[1,2-b]-1, 4-oxazine was unsuccessful. Work was also undertaken on various synthetic routes to diarylnaphth-1, 3-oxazine derivatives. Initial attempts were based on the preparation and cyclisation of 1-benzoylaminomethyl-2-naphthol. This having failed, an alternative approach involving the reaction of diarylketimines with 2-hydroxy-1-naphthaledhyde was investigated and successfully afforded 3,3-diaryl-3H-naphth[1,2-e]-1, 3-oxazines. In parallel with these studies the analogous syntheses of 2,2-diphenyl-2H-naphth[2,1-e]-1, 3-oxazine and 2,2-diaryl-2H-phenanthro[9,10-e]-1, 3-oxazines were also achieved.