The present invention is directed to a compound of the formula:
or pharmaceutically acceptable salts thereof and use of such compounds for treating proliferative diseases such as cancer, in mammals.
                            本发明涉及一种化合物,其
化学式为:或其药用可接受的盐,并且利用这些化合物来治疗哺乳动物中的增殖性疾病,如癌症。