Synthetic Approaches to 3H-Naphtho[2,1-b]pyrans and 2,3-Dihydro-1H-naphtho[2,1-b]pyrans

摘要

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.