Method of producing steroid derivatives

The present invention relates to a method of selectively producing 3-alkoxy-1,3,5(10)-triene-6-one-steroid derivatives, which are useful for drugs and diagnostic agents. A method of producing 3-alkoxy-1,3,5(10)-triene-6-one-steroid derivatives having, in the steroid skeleton thereof, a partial structure of A- and B-rings represented by formula (2): (wherein R represents an alkyl group, a cycloalkyl group, an alkenyl group, or an aralkyl group), including reacting a 19-norsteroid derivative having, in the steroid skeleton thereof, a partial structure of A- and B-rings represented by formula (1): with an alcohol represented by ROH (wherein R has the same meaning as defined above) and iodine in the absence of a rare earth compound catalyst. According to the method of the present invention, 3-alkoxy-1,3,5(10)-triene-6-one-steroids can be selectively produced from 19-norsteroides through a single reaction step without employment of a special catalyst.