Naslov
Synthesis of the first heteroannularly substituted ferrocene amino acid and isomeric carbamic acid derivatives containing chiral centres

Autori
Čakić Semenčić, Mojca ; Dropučić, Maja ; Barišić, Lidija ; Rapić, Vladimir

Izvornik
Croatica Chemica Acta (0011-1643) 79 (2006), 4; 599-612

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

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

Sažetak
The syntheses of N- and C-protected derivatives of 1'-(1-aminoethyl)ferrocene-1-carboxylic acid (Fcca) and of the 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 hydrolysed into Boc-Fcca/ Ac-Fcca and esterified into Boc-Fcca-OMe (11)/ Ac-Fcca-OMe (12). In a multistep sequence bromoferrocene was transformed into 1'-brominated Fea (15), Boc-Fea (16) and Ac-Fea (17), respectively. 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 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.

Izvorni jezik
Engleski

Znanstvena područja
Kemija

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