Applications naphthopyrans

In the reaction of 1-naphthol with 3-nitro-4-fluorobenzalmalononitrile in ethanol, catalyzed by secondary amines, nucleophilic displacement of fluorine competes with pyran ring closure. Application of a tertiary amine (N-methylmorpholine) leads to the selective formation of the corresponding aminochromene (94H(38)399). 2,3-, 1,8-Dihydrooxynaphthalenes 148 and 149 react with 1 or 2 equiv. of aromatic aldehyde 28 and MN 27a to yield naphthopyrans 150 and 151 or dipyrans 152 and 153 (90IJB885, 02RCB2238) (Scheme 53). 

The three main classes that have been much studied for ophthalmic applications are spiroindolinonaphthoxazines (see section 1.2.3), diarylnaphthopyrans (see section 1.2.4) and fulgides (see section 1.2.5). How these different photochromic classes match up to the desired criteria for use in lenses is shown in Table 1.9. From this it can be seen that fulgides exhibit only a fair fatigue resistance and spiroindolinonaphthoxazines suffer from a high temperature dependency. Consequently, for this photochromic outlet, naphthopyrans have become the molecules of choice. Typical... 

Chapter 3 (Benzo and naphthopyrans or chromenes). This chapter reviews another important type of thermoreversible photochromic compounds that have found application in the variable optical transmission materials field, specifically,... 

In later reports, Herscovici, eta/.,119 demonstrated the applicability of this technology to more complex allylic ethers. The example shown in Scheme 2.7.3 was utilized in an enantiospeciflc naphthopyran synthesis. 

Application of Suzuki cross-coupling methodology to thiophene boronates and bromo- or triflate-functionalised naphthols or naphthopyrans affords (2-thienyl)n derivatives of 3,3-diphenyl-3//-naphtho[2,l-6]pyrans (Scheme 11) <03EJO2799>. 

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