An optically active spirolactone compound is highly enantioselectively produced by using an iodoarene derivative which can be synthesized easily and which is not racemized easily. Community or social network rating data may be analyzed and weighting factors may be applied to the community or social network rating data. The attachable device uses a fastening method, a gripping method, a clamping method, a locking method or the like to attach the attachable cup to a toothbrush. Optionally, the power converter includes a low load circuit responsive to the control circuit that selectively couples current to the output terminal during the low load condition.