摘要:
Process for the formation of MeO-Peg-protected dihydroquinine or dihydro quinindine derivatives, new dihydroquinine-or dihyroquinidine derivatives as well as the use thereof. It is known that dihydroquinine or dihydroquinidine derivatives can be successfully used as ligands in the enantioselective dihydroxylation. The new disclosed ligand systems based on dihydroquinine/quinidine, unlike the prior art ligands, can be recycled after enantioselective dihydroxylation by precipitating and filtering the reaction medium, and be reused in the reaction medium. Also disclosed are the ligand systems (I) and (IV), process for preparing the same and their use in the enantioselective dihydroxiation of double bonds.
摘要:
It is known that dihydroquinine or dihydroquinidine derivatives can be successfully used as ligands in the enantioselective dihydroxylation. The new disclosed ligand systems based on dihydroquinine/quinidine, unlike the prior art ligands, can be recycled after enantioselective dihydroxylation by precipitating and filtering the reaction medium, and be reused in the reaction medium. Also disclosed are the ligand systems (I) and (IV), process for preparing the same and their use in the enantioselective dihydroxiation of double bonds.
摘要:
The invention involves a procedure for the catalytic enantioselective reduction of ketones to chiral alcohols. Heretofore, this reaction was carried out batch-wise. Because, in this procedure, one utilizes a catalyst increased in size with polymer, it is possible to carry out the reaction in a quasi-continuous manner in a membrane reactor. In contrast to the state of the art, one thus dramatically increases the operative life of the catalyst.
摘要:
A molecular weight-enlarged, homogeneously soluble ligand, useful in catalysts, particularly for the synthesis of enantiomerically enriched organic compounds, includes: a weight average molecular weight of at least 1000 g/mol; a molecular weight-enlarging polymer; optionally, a polymer linker; and at least one homochiral active center; wherein the active center is bound to the molecular weight-enlarging polymer through the polymer linker or is bound directly to the molecular weight-enlarging polymer.
摘要:
Molecular weight-enlarged, homogeneously soluble ligands are provided that are especially useful for hydrogenation catalysts, wherein the ligands contain homochiral active centers of bis(3,4-diarylphosphinyl)pyrrolidines, and their use in producing cataylsts for enantioselective reactions, as well as the catalysts thus produced.
摘要:
A plant peptide amidase from the flavedo of oranges is known; this can be obtained only in small quantities and is seasonal. The proposed new enzymes are microbial peptide amidases which can be obtained from micro-organisms recovered from soil samples in a “double screening” and grown. These microbial peptide amidases are particularly useful for (a) the production of peptides and N-terminal-protected amino acids, (b) racemate splitting of N-protected amino acid amides, (c) obtaining non-proteinogenous D-amino acids, and (d) obtaining new N&agr;-protected D-amino acid amides.
摘要:
The disclosure relates to a process for obtaining optically active L-.alpha.-aminocarboxylic acids from the corresponding racemic D,L,.alpha.-aminocarboxylic acids. The following steps are involved: (a) the D,L,.alpha.-aminocarboxylic acids are acetylated; (b) the N-acetyl-L-.alpha.-aminocarboxylic acid present in the mixture of N-acetyl-D,L,.alpha.-aminocarboxylic acids thus obtained is broken down enzymatically into the L-.alpha.-aminocarboxylic acid; (c) the L-.alpha.-aminocarboxylic acid is separated from the mixture, a quantity of a solution of N-acetyl-D(L)-.alpha.-aminocarboxylic acids and a quantity of acetate equivalent to the L-.alpha.-aminocarboxylic acid being retained; and (d) the N-acetyl-D(L)-.alpha.-aminocarboxylic acid is racemized and recycled for enzymatic breakdown. Known extraction processes involving steps (a) to (d) have the disadvantage of producing large quantities of salt. Specifically, the processes are far removed from the ideal equation, according to which one hundred percent of the acetic anhydride and the D,L,.alpha.-aminocarboxylic acids are converted to L-.alpha.-aminocarboxylic acids and acetic acid. Adjusting the retained solution from step (c) in such a way as to obtain a solution consisting essentially of N-acetyl-D-(L)-.alpha.-aminocarboxylic acid salt and free acetic acid in equilibrium with acetate and free N-acetyl-D(L)-.alpha.-aminocarboxylic acid and from which acetic acid is extracted by distillation makes it surprisingly easy to feed the solution formed as "mother liquor" following separation of the L-.alpha.-aminocarboxylic acid in the circuit and to achieve a materials balance as close as possible to the ideal.
摘要:
The invention relates to novel microorganisms, their use and method of producing L-.alpha.-amino acids. In particular, microorganisms DSM 7329 and 7330 are suitable for the production of L-.alpha.-amino acids from corresponding hydantoins or carbamoyl-.alpha.-amino acids. These novel microorganisms are simple to cultivate and make possible high L-.alpha.-amino acid yields from different substrates.
摘要:
The present invention is directed to an N-acetyl amino acid racemase (AAR) as well as the gene coding for it, to a plasmid, vector and microroganism containing the gene. A method of producing enantiomer-enriched amino acids, and derivatives thereof, is also provided.
摘要:
The invention concerns a process for the enzymatic preparation of protected di- and oligopeptides and the separation of the protective groups used. The process according to the invention enables peptides to be synthesized simply and economically and the protective group to be separated carefully. The process comprises three reaction steps: 1. Preparation of N-carbamoyl amino acid or N-carbamoyl amino acid derivatives; 2. Formation of the peptide bond between the carbamoyl-protected electrophile and nucelophile; and 3. Separation of the carbamoyl-protective group.