Benzodioxino-naphtho[1,2-b]pyran compounds having particularly advantageous
photochromic properties, such as, high sensitivity/coloration, two
distinct absorption bands in the 430-500 nm range and 520-620 nm range of
the visible spectrum may be generally described as a naphthopyran having a
central nucleus of the formula:
##STR1##
wherein F is a 1,4-benzodioxine ring
##STR2##
with its 2,3 positions fused to the i, j, or k faces; and R.sub.1 and
R.sub.2 are the atoms or groups providing photochromic properties to the
naphthopyran.
