sentences:  The S-form then goes through a Pictet-Spengler type reaction followed by a series of O-methylations and the removal of glucose, with O-methyltransferases and a glycosidase, to form proemetine.Proemetine then reacts with another dopamine molecule to form 7'-O-demethylcephaeline.The final products are then produced with a 7'-O-methylation to make cephaeline and a 6'-O-methylation successively to make emetine.