Substitution on the Indoline Ring Moiety

The photochromic response of spirooxazines was shown to be somewhat affected by the substituent on the indolino nitrogen5 (Table 2.2). For various 1-alkyl-5,6-dimethyl-9 -methoxy NISOs in cellulose acetobutyrate, photochromic activity increased in the order 1-methyl 1-ethyl 1- n-propyl l- -butyl. However, the effect was not straightforward. 

Chu 6 claimed that the addition of a trifluoromethyl group to the 4- or 6-position of indolinospironaphthoxazine resulted in a similar hypsochromic shift. 

The synthesis of 6 -indolino-l,3,3 -trimethylspiro[indolino-2,3 -[3/f]naphth-[2,l-A][l,4]oxazine] (compound 7) is given later. 

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