Synthesis of carbosilane dendritic wedges and their use for the construction of dendritic receptors

Dendritic polarizing agents for DNP SENS

Dendrimer-shielded polarizing agents for the application of DNP SENS to reactive surfaces.

Dynamic Nuclear Polarization Surface Enhanced NMR Spectroscopy (DNP SENS) is an effective method to significantly improve solid-state NMR investigation of solid surfaces. The presence of unpaired electrons (polarizing agents) is crucial for DNP, but it has drawbacks such as leading to faster nuclear spin relaxation, or even reaction with the substrate under investigation. The latter can be a particular problem for heterogeneous catalysts. Here, we present a series of carbosilane-based dendritic polarizing agents, in which the bulky dendrimer can reduce the interaction between the solid surface and the free radical. We thereby preserve long nuclear T′₂ of the surface species, and even successfully enhance a reactive heterogeneous metathesis catalyst.

Synthesis and Anti-Tumor Activity of Cyclodepsipeptides Paecilodepsipeptide A

paecilodepsipeptide A was first synthesized by retrosynthesis methods. the structures were determined by Mass Spectrometry and NMR spectroscopy, and the anti-tumor activities on human hepatocellular carcinoma cell line (SMMC-7721) and human lymphoma cell line (Raji) were examined by MTT. The result showed that the rate of Paecilodepsipeptide A was 72% by retrosynthesis methods. The structures of the synthesized product were identified by 1H NMR and 13C NMR spectra, which is identical to the natural product. The product has remarkable anti-proliferation activity on SMMC-7721 and Raji, which showed good anti-tumor activity. IC50 was 8.97 μmol/L and 11.13 μmol/L respectively, The total synthesis of Paecilodepsipeptide A is significant to further study its derivatives and develop novel antitumor drugs.