Microbial enantioselective removal of the N-benzyloxycarbonyl amino protecting group
In order to deprotect N-carbobenzoxy-l-aminoacids (Cbz-AA) and related compounds, a series of microorganisms was selected from soil by enrichment cultures with Cbz-l-Glu as sole nitrogen source. A lyophilized whole-cell preparation of two Arthrobacter sp. strains grown on Cbz-Glu or Cbz-Gly exhibited a high cleavage activity. The conditions of hydrolysis have been optimized and a quantitative enantioselective deprotection of several Cbz-dl-amino acids was obtained, as well as the deprotection of N-carbamoylester derivatives of several synthetic amino compounds. The preparation of Cbz-d-allylglycine and l-allylglycine in high yield and high optical purity is described as an application of this method.
Maurs, Michele,Acher, Francine,Azerad, Robert
p. 22 - 26
(2012/10/29)
Stereospecific Alkylation of the Schiff Base Ester of Alanine with 2-Substituted-(E)- and -(Z)-vinyl Bromides. An Efficient Synthesis of 2-Methyl-(E)-3,4-didehydroglutamic Acid, a Potent Substrate-Induced Irreversible Inhibitor of L-Glutamate-1-decarboxylase.
The nucleophilic vinylic substitution by the enolate of methyl N-benzylidenealanate (1) of (E)- and (Z)-vinylbromides 4 and 5 has been examined as an approach to the synthesis of the E and Z isomers of 2-methyl-3,4-didehydroglutamic acid.Under aprotic conditions, the nucleophilic displacement has been found to proceed stereospecifically with retention of configuration of the double bond to afford in good yield the corresponding (E)- and (Z)-substituted products.The configuration of the substitution products has been assigned from the analysis of their 1H NMR spectra on the basis of the value of the coupling constant of the vicinal vinyl ic protons.Subsequent removal of the protecting groups from the substitution products 6 in the E series gives the corresponding 2-methyl-(E)-3,4-didehydroglutamic acid derivatives 2 in good yield.The Z isomers 3 prove to be very unstable and have not been isolated.
Bey, Philippe,Vevert, Jean Paul
p. 3249 - 3253
(2007/10/02)
The preparation of optically active alpha-C-substituted glutamic acid.