[2-{2-[2,2-Bis-(diethoxy-phosphoryl)-ethylamino]-ethylamino}-1-(diethoxy-phosphoryl)-ethyl]-phosphonic acid diethyl ester

tetraethyl (3-butyn-1-ylidene)-1,1-bisphosphonate

tetraethyl (5-oxopentylidene)bisphosphonate

tetraethyl 3,3-bis(benzyloxycarbonyl)propylene bisphosphonate

tetraethyl (17β (3-benzyloxyoestra-1,3,5(10)-trienyl)oxycarbonyl) (methyloxycarbonyl) propylene bisphosphonate