Fluoroboron compound having aromatic ring or salt thereof, and method for producing compound having cyclic ether-fused aromatic ring using the same

A fluoroboron compound or a salt thereof,

• wherein said fluoroboron compound or the salt thereof is capable of forming a cyclic ether fused with an aromatic ring by an intramolecular alkoxymethylation reaction,
• wherein said fluoroboron compound is represented by the following formula (I):
• (wherein the moiety represented by the formula
• represents an aromatic ring which may or may not have substituents other than L and —R—O—CH2BF3M groups, wherein said aromatic ring is selected from the group consisting of benzene, naphthalene, pyridine and quinoline;
• L represents a leaving group selected from the group consisting of a halogen atom, a substituted alkylsulfonyloxy group, an unsubstituted alkylsulfonyloxy group, a substituted arylsulfonyloxy group and an unsubstituted arylsulfonyloxy group;
• R represents a substituted or unsubstituted alkylene group of 1 or 2 carbon atoms;
• M represents an alkali metal cation, [N(R1)(R2)(R3)(R4)]+, or [P(R1)(R2)(R3)(R4)]+, (in which R1, R2, R3, and R4 each independently represents a C1-6 alkyl group or a C7-16 aralkyl group);
• with the proviso that L and —R—OCH2BF3M are respectively located on contiguous carbon atoms on the aromatic ring or, in the case where the aromatic ring is a fused aromatic ring formed of 2 rings, on two carbon atoms adjacent to one carbon at the fused position.