BICYCLIC COMPOUND AND PHARMACEUTICAL USE THEREOF

摘要

Disclosed is a compound represented by the following formula: (wherein R1 presents an optionally substituted hydrocarbon group, an optionally substit uted amino group, an optionally substituted hydroxy group or an optionally s ubstituted heterocyclic group; R2 represents a hydrogen atom or an optionall y substituted hydrocarbon group; Xa and Xb each represents C, N, O or S; Xc and Xd each represents C or N; m represents a number of 0-2; n represents a number of 1-3; ring A represents an optionally substituted 5-membered ring; ring B represents an optionally substituted 6-membered ring; and ring C repr esents an optionally substituted 3- to 5-membered ring; provided that when X a, Xc and Xd are C, Xb is N or S) or a salt thereof, which is useful as an a gent for prevention/treatment of diseases associated with action of melatoni n.