The invention relates to a new process for the preparation of compounds of the formula (I) ##STR1## in which R.sub.1 denotes alkyl and R.sub.2 denotes H, acetyl or propionyl, by addition of compounds of the formula II ##STR2## onto compounds of the formula III, using radical-formers, the radical-formers being used being compounds of the general formula IV ##STR3## in which R.sub.3 denotes alkyl or phenyl and R.sub.4 denotes alkyl, the reaction being carried out at temperatures in the range from 50.degree. to 100.degree. C., and, for the preparation of compounds of the formula I where R.sub.2 is H, then splitting off the radical R.sub.2.sup.'. Using this process, the compounds of the formula I are obtained in high yield and particular purity.
本发明涉及一种新的制备式(I)化合物的方法,其中R.sub.1表示烷基,R.sub.2表示H、乙酰基或丙酰基,通过将式II的化合物加到式III的化合物中,使用自由基
引发剂,所使用的自由基
引发剂是通式IV的化合物,其中R.sub.3表示烷基或苯基,R.sub.4表示烷基,反应在50℃至100℃的温度范围内进行,对于制备R.sub.2为H的式I化合物,然后分离出自由基R.sub.2.sup.'。使用这种方法,可以高产率和特定纯度地得到式I的化合物。