| 摘要 |
PROBLEM TO BE SOLVED: To provide a photochromic compound having a high durability, a reduced initial coloration, and a high discoloration rate. SOLUTION: A pyran compound represented by formula (1) is formed by the fusion of pyran and a ring having at least one specified Si-containing organic group (e.g. a trimethylsilyl or 1-chlorotetramethyldisiloxyl group) bonded thereto. In formula (1), an X-containing divalent cyclic group is an unsubstituted aromatic hydrocarbon ring or an optionally substituted or unsubstituted unsaturated heterocyclic ring; R<SB>1</SB>and R<SB>2</SB>are indipendently a substituted group such as an alkyl group or the like; R<SB>3</SB>is a specified Si-containing organic use group such as trimethylsilyl or 1-chlorotetramethyldisiloxyl group; and R<SB>4</SB>is a hydroxyl group, an alkyl group, or the like. COPYRIGHT: (C)2004,JPO&NCIPI
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