| 摘要 |
A heterobenzopyran compound of general formula (1), wherein R1 represents a five-membered heterocyclic group containing one or more hetero atoms and fused either to the f-face or the g-face of the benzo moiety of the benzopyran skeleton, the said heterocyclic group being fused in such a manner that the hetero atom in the heterocyclic group is linked directly to a carbon atom on the said benzo moiety, and, optionally, the said heterocyclic group has fused thereto a furthercarbocyclic or heterocyclic group or is substituted with a group of formula R4 as defined below; each of R2 and R3, which may be the same or different, independently represents a carbocyclic or heterocyclic group, or R2 and R3 takentogether with the carbon atom to which they are attached form a carbocyclic or heterocyclic ring system; and R4 represents a hydrogen atom or a substituent selected from alkyl, alkoxy, aryl, aryloxy, heteroaryl, halogen, substituted or unsubstituted amino, azo, imino, amide, ester, cyano, trifluoromethyl or nitro. The heterobenzopyran compounds of the invention are useful as photochromic transparencies for cars and aircraft.
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