The invention relates to compound of formula (I) wherein: B represents hydrogen, COOR, CONRR', or (C.sub.1-C.sub.6)alkyl substituted by COOR, CONRR', or OR, G.sub.1 represents --X'--(CH.sub.2).sub.n--X--(CH.sub.2).sub.m--X''-- chain wherein X, X', X'', n and m are as defined in the description, Cy represents a grouping of formula (II) or (III): G.sub.2 represents alkylene chain as defined in the description, and A represents NRCOR', NRCSR', CONRR', CSNRR', NRCONR'R'', or NRCSNR'R''. and medicinal products containing the same which are useful in treating or preventing melatoninergic disorders.