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

Synthetic accesses to formylated photochromic 3,3-diphenyl-[3H]-naphthopyra ns (or 2H-benzochromenes) are developed through classical cyclization betwe en appropriate hydroxynaphthaldehydes and 1,1-diphenylpropyne-1-ol and also via substituent transformations on the naphthopyran skeleton including bro mine/lithium exchange and the oxidation of an hydroxymethyl group. Examples of formyl group reactivity (Wittig and Knoevenagel reactions, imine format ion) from these compounds are given, showing their interest in the subseque nt preparation of supramolecular systems involving a photoreactive entity. (C) 1999 Elsevier Science Ltd. All rights reserved.