Efficient Enzymatic Routes for the Synthesis of New Eight-membered Cyclic β-Amino Acid and β-Lactam Enantiomers

Green Strategies for the Preparation of Enantiomeric 5-8-Membered Carbocyclic β-Amino Acid Derivatives through CALB-Catalyzed Hydrolysis

Candida antarctica lipase B-catalyzed hydrolysis of carbocyclic 5−8-membered cis β-amino esters was carried out in green organic media, under solvent-free and ball-milling conditions. In accordance with the high enantioselectivity factor (E > 200) observed in organic media, the preparative-scale resolutions of β-amino esters were performed in tBuOMe at 65 °C. The unreacted β-amino ester enantiomers (1R,2S) and product β-amino acid enantiomers (1S,2R) were obtained with modest to excellent enantiomeric excess (ee) values (ees > 62% and eep > 96%) and in good chemical yields (>25%) in one or two steps. The enantiomers were easily separated by organic solvent/H2O extraction.

Alicyclic β- and γ-Amino Acids: Useful Scaffolds for the Stereocontrolled Access to Amino Acid-Based Carbocyclic Nucleoside Analogs

Stereocontrolled synthesis of some amino acid-based carbocyclic nucleoside analogs containing ring C=C bond has been performed on β- and γ-lactam basis. Key steps were N-arylation of readily available β- or γ-lactam-derived amino ester isomers and amino alcohols with 5-amino-4,6-dichloropyrimidine; ring closure of the formed adduct with HC(OMe)₃ and nucleophilic displacement of chlorine with various N-nucleophiles in the resulting 6-chloropurine moiety.