A new approach to β-amino acids: biotransformation of N-protected β-amino nitriles

Influence of relative configuration of disubstituted cyclopentanes and ‐hexanes on 13C shifts

“…[9a] For substances listed in Tables 1 and 2, 13 C data for both the cis and the trans forms were available either from this lab or from the literature (only for very few diastereomer pairs of this series 13 C data were available and, to our knowledge, the list is comprehensive; see References). Unless otherwise stated, the spectra were recorded in CDCl 3 .…”

Nitrilase‐ and Nitrile Hydratase‐Catalyzed Enantioselective Preparation of Non‐Proteinogenic Amino Acids

“…R312, and R. erythropolis NCIMB 11540, containing the nitrile hydratase/amidase enzyme system, are effi cient catalysts for stereoselective microbial hydrolysis of N -protected carbocyclic β -amino nitriles ( ± ) -1a -( ± ) -4a , to β -amino acids 1c -4c and amides 1b -4b , respectively (Scheme 15.1 ) [33,34] .…”

Nitrilase‐Catalyzed Enantioselective Synthesis of Pyrrolidine‐ and Piperidinecarboxylic Acids

“…[8][9][10] Current enzyme engineering is concerned with modification of particular nitrilases to prepare pipecolic acid as well as further heterocyclic acids of commercial importance. [14] A comparison of the present heterocyclic b-amino nitriles (AE )-1a and (AE )-3a [15] with carbocyclic bamino nitrile analogues bearing the amino group in an exocyclic position, [16][17][18] evidences a strictly diverging reactivity with nitrilases: the former heterocycles are excellent substrates, the carbocyclic compounds are non-substrates. Contrary to nitrilases though, such cyclopentane-and cyclohexanecarbonitriles can be transformed enantiosectively to b-amino acids by nitrile hydratases in whole cells.…”

“…Contrary to nitrilases though, such cyclopentane-and cyclohexanecarbonitriles can be transformed enantiosectively to b-amino acids by nitrile hydratases in whole cells. [16][17][18] This low substrate specificity of nitrilases regarding the carbocyclic structures is likely due to a sterically unfavourable position of the exocyclic amino group in the 2-position. A similar situation is encountered in (AE )-4a, where the protecting group of the ring nitrogen atom is acting in the manner of an exocyclic substituent in 2-position, thus resulting in substantial hindrance for the enzyme.…”