Preparation and structural features of lithium cyclopentadienides that contain amino acid-derived Cp-substituents

Treatment of N-protected amino acid active esters, e.g., 3, formed by, the reaction of N,N-dibenzyl-alanine (2) with DCC and hydroxybenztriazole, with 2 molar equiv of CpLi gives the corresponding amino acid-substituted Cp-an ion equivalents (e.g., 4). The X-ray crystal structure analysis of 4 has re vealed a dimeric pentafuluenolate-type structure. Reaction of FeCl2 or (PPh 3)(3)RuCl2 with compound 4 and related reagents yields the respective 1,1'- difunctionalized metallocenes (7, 8).