No abstract

No abstract

A dynamic combinatorial library of thiocolchicine-podophyllotoxin derivatives based on the disulfide bond exchange reaction is described. The influence of a biological target on the composition of the reaction mixture has been demonstrated. Use of high-resolution ESI mass spectrometry to evaluate the composition of the mixture shows promise for the design of new large libraries. The biological evaluation demonstrates that formation of a divalent compound affords a new chemical entity whose biological activity is not merely the sum of the single ligands activities, thus reflecting a different interaction with the biological target.

[reaction: see text] The first total enantiosynthesis of the biologically active alkaloid (-)-cytisine is reported, featuring a ruthenium-catalyzed RCM reaction as the key step. The approach relies on readily available cis-piperidine-3,5-dimethanol monoacetate as the chiral building block, and it is suited for achieving the target compound in both enantiomeric forms.

Addition of Grignard reagents to chiral imines derived from isatine afforded chiral, optically enriched 3-substituted 3-aminooxindoles in satisfactory yields and diastereoisomeric ratios. A general protocol is described for the addition of alkyl, alkenyl, and aryl Grignard reagents. In one case, the absolute configuration at C3 was determined and the selective N-deprotection was described, enabling further synthetic transformations of the reaction product.