Synthesis and photochromic properties of substituted 3H-naphtho[2,1-b]pyrans

The synthesis and spectroscopic properties of novel 3H-naphtho[2, 1-b]pyrans are described. Subtle variation of the colour of the photo-generated merocyanine dyes derived from these naphthopyrans can be accomplished by controlling the steric interactions between a terminal pyrrolidine donor group and a proximal substituent. (C) 2004 Elsevier Ltd. All rights reserved.