Synthetic approaches to 3H‐naphtho[2,1‐b]pyrans and 2,3‐dihydro‐1H‐naphtho[2,1‐b]pyrans

Abstract

in Wiley InterScience (www.interscience.wiley.com).Naphtho [2,1-b]pyran nuclei are prevalent in natural products with significant biological and medicinal properties. 3,3-Disubstituted 3H-naphtho[2,1-b]pyrans are photochromic and find use in electronic display systems, ophthalmic lenses, optical switches, and temporary or permanent memories. Of the various possible structural isomers of naphthopyran framework, this review is an account of reported synthetic procedures to produce 3H-naphtho[2,1-b]pyrans and their dihydro analogs, 2,3-dihydro-1H-naphtho[2,1-b]pyrans. The advantages and disadvantages of each procedure in terms of yields, complexity, formation of side-products, use of uncommon/expensive reagents, etc., are also described.

Oxygen‐Doped PAH Electrochromes: Difurano, Dipyrano, and Furano‐Pyrano Containing Naphthalene‐Cored Molecules

“…[64,65] Taking advantage of their low oxidation potentials, O-doped PAHs can be considered as one of the promising classes of electrochromic small molecules. Amongst all O-doped molecules, [66] those featuring furanyl, [67][68][69][70][71] pyranyl, [72][73][74] or oxepinyl [75,76] rings are of particular interest to the area of optoelectronics, [66] especially as p-type semiconductors. [67] One of the most well-known examples of an O-doped electrochrome can be found in the peri-xanthenoxanthene (PXX, Figure 1), [77,78] a well-known molecular p-type semiconductor that was one of the first pyranyl-conjugates to exhibit electrochromic properties (from yellow to blue).…”