Synthesis of methanesulfone-containing tetrasubstituted carbon stereocenters.

A methanesulfonylation reaction for the synthesis of sulfone-containing tetrasubstituted carbon stereocenters is described for the first time by simple treatment of indanedione-chromanone synthons with Et3N and easily accessible MsCl without any use of organometallic chemistry. This technology gave the corresponding valuable chromone-based 2-methanesulfonylated 1,3-indanediones in good yields (up to 89% yield) under mild conditions. The present work provides an attractive strategy for the construction of biologically interesting sulfone-containing tetrasubstituted carbon stereocenters, which might be valuable in medicinal chemistry.

[Expression of proteinase cathepsin L1 gene of Schistosoma japonicum in Escherichia coli].

OBJECTIVE: To express the proteinase cathepsin L1 gene of Schistosoma japonicum (SjCL1) in Escherichia coli JM109 cells. METHODS: The SjCL1 gene was amplified from the recombinant plasmid pcDNA3-SjCL1 by PCR. The gene was cloned into a prokaryotic expression vector pGEX4T-1 to construct a recombinant plasmid pGEX-SjCL1. The E. coli JM109 cells were transformed with the recombinant plasmid pGEX-SjCL1 and the transformants were induced by IPTG to express the recombinant protein, the target protein was then identified by SDS-PAGE and Western blotting. RESULTS: A 1 kb length PCR product was obtained and a recombinant plasmid pGEX-SjCL1 was constructed. The expression product was detected by SDS-PAGE and Western blotting and an expression band about 62000 was found. CONCLUSION: The SjCL1 gene is effectively expressed in the E. coli JM109 cells.