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Synthesis of the First Heteroannularly Substituted Ferrocene Amino Acid and Isomeric Carbamic Acid Derivatives Containing Chiral Centres

Mojca Čakić Semenčić
Maja Dropučić
Lidija Barišić
Vladimir Rapić

Sažetak

Syntheses of N- and C-protected derivatives of 1'-(1-aminoethyl)ferrocene-1-carboxylic acid (Fcca) and isomeric carbamic acid are reported. The first attempt to prepare N-Ac-Fcca (8) by cleavage of 1-[1-(acetamido)ethyl]-1'-(o-chlorobenzoyl)ferrocene (7) with t-BuOK/H2O/GLYME failed. Friedel-Crafts reactions of N-substituted (1-ferrocenylethyl)amines [Boc-Fea (5) and Ac-Fea (6)] with ClCOSMe/AlCl3 gave the corresponding heteroannularly substituted thioesters 9/10, which were hydrolyzed into Boc-Fcca/Ac-Fcca and esterified into Boc-Fcca-OMe (11)/ Ac-Fcca-OMe (12). In a multi-step sequence, bromoferrocene was transformed into 1’- brominated Fea (15), Boc-Fea (16) and Ac-Fea (17). Lithiation/ethoxycarbonylation of these bromine compounds gave the corresponding carbamic esters 18 and 19, instead of the expected Fcca esters. By lithiation/carboxylation and subsequent esterification, 5, 6, 16 and 17 were converted into the desired 11 and 12. 1'-Acetylferrocene-1-carboxylic acid (21) was transformed into oxime 22 and oxime-ester 23. Hydrogenation of this intermediate resulted in formation of Fcca-OMe (24) in very good yield. The structure of the compounds prepared was confirmed by HRMS and spectroscopic analyses.

Ključne riječi

ferrocene chiral amino acid; ferrocene chiral carbamic acid; oxime reduction; lithiation; carboxylation

Hrčak ID:

5806

URI

https://hrcak.srce.hr/5806

Datum izdavanja:

13.12.2006.

Posjeta: 3.849 *