250347-99-0Relevant academic research and scientific papers
The synthesis of novel cyclic β-amino acids as intermediates for the preparation of bicyclic β-lactams
Maison, Wolfgang,Kosten, Marc,Charpy, Audrey,Kintscher-Langenhagen, Jürgen,Schlemminger, Imre,Lützen, Arne,Westerhoff, Ole,Martens, Jürgen
, p. 2433 - 2441 (2007/10/03)
Several derivatives of homopipecolic acid are prepared by α-amino alkylation of malonic acid with cyclic imines 6 and 7. These are prepared on a large scale and with different substitution patterns. The β-amino acids 8 and 9 were formed in high yield and with remarkable diastereoselectivity if chiral imines are used as starting materials. The diastereoselectivity of the amino alkylation leading to homopipecolic acid analogues is compared to those of thiazolidineacetic acids by epimerisation experiments. A method for resolution of the obtained racemic β-amino acids by diastereomeric salt formation is described. The β-amino acids 9 and 15 were converted into their corresponding carbacepham analogues 14 and isopenam 16. The isopenam endo-16 was selectively epimerised by mild basic treatment of the N/S-acetal to give an exo-configured precursor of isopenicillin G.
Synthesis of novel pipecolic acid derivatives: A multicomponent approach from 3, 4, 5, 6-tetrahydropyridines
Maison, Wolfgang,Liitzcn, Arne,Kosten, Marc,Schlcmminger, Imre,Westerhoff, Ole,Martens, Juergen
, p. 3515 - 3525 (2007/10/03)
A simple approach to several derivatives of pipecolic acid is via a multicomponent reaction starting from cyclic imines 2, which are synthesized on a large scale and with different substitution patterns. The protected amino acids 3 are formed in high yields. In cases where chiral imines are used the target compounds are obtained with remarkable diastereoselectivity. Bisamides 3 serve as versatile precursors for the preparation of a wide range of amino acid derivatives. Different methods of hydrolysis of 3 lead to the free pipecolic acids or its derivatives. Employment of methanol or ethanethiol as a nucleophile in the acid-mediated conversion of enamides 3 results in W-acylated amino acid esters 5. Furthermore a method for the resolution of the obtained racemic a-amino acids via diastereomeric salt formation is described. The Royal Society of Chemistry 1999.
