Catalytic Asymmetric Construction of Chiral Polysubstituted 3-Azabicyclo[3.1.1]heptanes by Copper-Catalyzed Stereoselective Formal [4π+2σ] Cycloaddition.

The direct construction of bioisosteric compounds enriched in Csp3 content represents an attractive and dependable approach to imbuing biologically active molecules with enhanced three-dimensional characteristics, finding wide utility across the synthetic and medicinal chemistry community. Despite recent advancements in the synthesis of (aza)-bicyclo[3.1.1]heptanes (BCHeps and aza-BCHeps), which serve as meta-substituted (aza)-arene bioisosteres, the enantioselective assembly of chiral 3-aza-BCHeps remains a coveted goal yet to be achieved. Here, we disclose an unprecedented copper-catalyzed asymmetric formal [4π+2σ] cycloaddition of bicyclo[1.1.0]butanes (BCBs) and azomethine ylides, furnishing a diverse array of enantioenriched 3-aza-BCHeps with exceptional levels of diastereo- and enantioselectivites (51 examples, all >20:1 dr, mostly 97-99% ee). Both mono- and disubstituted BCBs are well compatible with this protocol, offering an enticing route for the efficient synthesis of challenging tetrasubstituted bicyclic products bearing two quaternary centers. The synthetic significance of this methodology is further demonstrated by the successful preparation of several piperidine drug analogues.

[Optimization of expression and purification protocol for human scFv antibody against ß-amyloid peptide].

AIM: To optimize the expression and purification protocol for human scFv antibody against-amyloid peptide. METHODS: Expression of E3 scFv was induced by different concentrations of IPTG under the fixed condition of time period and temperature, and the optimal concentration of IPTG was determined by SDS-PAGE analysis on E3 scFv expression level. Furthermore, elution buffer with different concentrations of imidazole was used for pre-eluting to determine the optimal pre-eluting condition by Western blotting against E3 scFv. RESULTS: We obtained the highest expression of E3 scFv after 18 h induction with 0.1 mmol/L IPTG under 20 Degrees Celsius. In addition, Western blotting indicated the highest purity of E3 scFv when the resin was pre-eluted with the buffer containing 10 mmol/L imidazole. CONCLUSION: Through optimizing the above mentioned conditions, we established an improved strategy for high expression and efficient purification of E3 scFv, which paves the way for further research.