STEREOSPECIFIC COORDINATION OF L-HYDROXYPROLINE ESTERS WITH TRIOSMIUMCLUSTERS

The reactions of cluster (mu-H)Os-3(CO)(10)(mu-OH) with ethyl and isop ropyl esters of L-oxyproline were studied. In the presence of Me(3)NO intermediate complex 3(mu-H)Os-3(CO)(9)(mu-OH)L (L - isopropyl ester o f L-oxyproline) is formed, which slowly converts to the more stable cl uster mu-H)Os-3(CO)(9){mu,eta(2)-OCHCH2CH(COOPri)NHCH2}. Cluster compl exes containing chelate-bridging heterocycles were also obtained by he ating(mu-H)Os-3(CO)(10)(mu-OH) with esters of L-oxyproline. In both ca ses, only one of the possible diastereomeric complexes (mu-H)Os-3(CO)( 9){mu,eta(2)-OCHCH2CH(COOPri)NHCH2} (R = Et, Pr-i) is formed, which in dicates that the reactions are stereospecific. Based on analysis of Dr eiding's models, an attempt to determine the absolute configuration of the obtained clusters was made.