Xin-Jie Chu - Shanghai, CN George Kenneth Ehrlich - Bronx NY, US Jin-Jun Liu - Warren Township NJ, US Hanspeter Michel - Bloomfield NJ, US Binh Thanh Vu - North Caldwell NJ, US Chunlin Zhao - Shanghai, CN
There are provided compounds of the formulawherein X, Y, Z, R, Rand Rare as described hereinand enantiomers and pharmaceutically acceptable salts and esters thereof. The compounds are useful as anticancer agents.