MORPHINAN DERIVATIVE

摘要

A morphinan derivative represented by general formula (I) or a pharmacologically acceptable acid addition salt thereof which is usable as an analgesic. In general formula (I): R1 represents C1-6 alkyl, C2-6 alkenyl, cycloalkylalkyl [said cycloalkylalkyl consisting of a C3-6 cycloalkyl moiety and a C1-3 alkylene moiety], aralkyl [said aralkyl consisting of a C6-10 aryl moiety and a C1-3 alkylene moiety], etc.; R2 represents C6-10 aryl, aralkyl [said aralkyl consisting of a C6-10 aryl moiety and a C1-3 alkylene moiety], etc.; R3 and R4 together form -O-(CHR6)m-O- [wherein R6 represents hydrogen, etc.; and m represents 1, etc.], etc.; R5 represents hydrogen, hydroxy, etc.; X represents O or CH2; A represents CH2 or C=O; and B represents C=O or a bond, provided that when A is C=O, B is a bond.